Police detained 70 people in Istanbul as they tried to march. Garment workers in Cambodia defied a government ban to demand higher wages, and businesses in Puerto Rico were boarded up as the U.S. territory braced for a huge strike over austerity measures. In Paris, police fired tear gas and used clubs on rowdy protesters at a march that included calls to defeat far-right presidential candidate Marine Le Pen.
Some May Day events around the world:
A May Day march in Paris has turned violent less than a week before the runoff French presidential election.
A few hundred protesters started throwing gasoline bombs and other objects at police at the front end of what started as a peaceful union march in the French capital on Monday.
Police responded with tear gas and truncheons. Riot police clubbed some protesters who were pushed up against a wall on a tree-lined avenue.
The annual march to celebrate workers' rights this year included calls to block far-right presidential candidate Marine Le Pen from winning the presidency during a runoff election on Sunday.
The violent protesters were not carrying any union or election paraphernalia.
Video showed riot police surrounding the protesters disrupting the march after isolating most of them from the rest of the crowd near the Place de la Bastille. However, some continued to lob firebombs that exploded into flames in the street.
It was not immediately clear if anyone was injured in the incidents.
They appeared to be from the same fringe groups that have targeted anti-government protests in the past.
The union activists continued to march separately, although police are interrupting to check bags for gasoline bombs.
Businesses in Puerto Rico have been boarded up as the U.S. territory braces for a May Day strike organized by opponents of austerity measures amid a deep economic crisis.
Dozens of people wearing black T-shirts blocked a main road in the capital of San Juan and marched toward the financial center. They banged large wooden placards painted with a black Puerto Rican flag against the ground.
Thousands of protesters are expected Monday as Puerto Rico teeters on the edge of a possible bankruptcy-like procedure.
A measure that has protected the territory from creditor lawsuits expires at midnight, and the government has struggled to reach a deal with bondholders to restructure part of its $70 billion debt.
Police in Istanbul detained more than 70 people who tried to march to iconic Taksim Square in defiance of a ban on holding May Day events there. The square was declared off limits to demonstrations for a third year running and police blocked points of entry, allowing only small groups of labor union representatives to lay wreaths at a monument there.
Taksim holds a symbolic value for Turkey's labor movement. In 1977, shots were fired into a May Day crowd from a nearby building, killing 34 people.
Main trade unions groups have agreed to hold large rallies at government-designated spots in Istanbul and Ankara but small groups were expected to try to reach Taksim.
A protester has briefly disrupted the start of Cuba's largest annual political event, sprinting in front of May Day marchers with a U.S. flag before being tackled and dragged away.
President Raul Castro watched along with other military and civilian leaders and foreign dignitaries as the man broke through security and ran ahead of the tens of thousands in the pro-government march.
Plainclothes officers struggled to control the man but eventually lifted him off the ground and hauled him away in front of foreign and Cuban journalists covering the parade.
Monday's protest was a surprising breach of security at a government-organized event where agents line the route.
Castro has said he will step down as president in February, making this his last May Day parade as head of state.
Two May Day marches were held in Moscow, both drawing from nostalgia for Soviet times.
First, a crowd that police estimated at about 130,000 people paraded across the cobblestones of Red Square, the site of Soviet-era May Day celebrations. The tradition was revived in 2014 after Russia's annexation of Crimea and is seen as part of President Vladimir Putin's efforts to stoke patriotic feelings.
Marchers, organized by official trade unions, waved the Russian tricolor flag and carried white, blue and red balloons.
The second march was led by the Communists, who over the years have tried to keep the May Day tradition alive. Their march, which skirted Red Square, drew several thousand people.
Many carried red flags with the Soviet hammer and sickle, but there was little honoring of Soviet leaders Vladimir Lenin and Josef Stalin compared to previous years.
The Communist Party still has a faction in the Russian parliament but rarely poses any opposition to the Kremlin.
South African President Jacob Zuma was jeered by labor unionists and his May Day speech was cancelled after scuffles broke out between his supporters and workers chanting for him to step down.
Zuma, who is facing calls to resign after a string of scandals, was expected to call for unity between his ruling party, the African National Congress, and labor unions at the rally in Bloemfontein.
Groups in the crowd booed the president and clashed with his supporters before he could speak.
All speeches scheduled for the event then were cancelled by the Congress of South African Trade Unions, the country's largest body of unions.
The organization has called for the 75-year-old Zuma to resign.
Zuma once a popular figure among South Africa's workers, was eventually ushered away by his bodyguards.
Spain's two major unions called for marches in over 70 cities under the slogan "No More Excuses." UGT and CC.OO unions on Monday demanded that Spain's conservative government roll back its labor reforms that made it cheaper to fire workers and increase wages and pensions.
CC.OO general secretary Ignacio Fernandez Toxo said "Spain has been growing for two years and now it is time for the economy to align itself with the needs of the people."
He spoke at a march of several thousand people in Madrid, which he led alongside UGT leader Josep Maria Alvarez. Thousands more marched in Barcelona, while other rallies were held in Seville, Valencia and other cities.
Under conservative Prime Minister Mariano Rajoy, Spain's economy has rebounded and unemployment has dropped from 27 percent in 2013 to 19 percent, but that is still the second-highest unemployment rate in the 28-nation European Union behind Greece.
Rajoy thanked Spain's workers on Twitter: "I appreciate your contribution to the economic recovery. The government is working to create more and better jobs."
Labor union and left-wing activists appealed for unity in order to oppose Poland's current conservative government as they marked May Day with a parade in Warsaw.
The rally and a march Monday was by the All-Poland Alliance of Trade Unions and by the Democratic Left Alliance, which lost all parliament seats in the 2015 election that brought the conservative populist Law and Justice party to power.
Sebastian Wierzbicki of the SLD said the left wing needs to protect workers' rights but also focus on civic rights and human dignity.
Riot police watched carefully as more than 1,000 garment workers defied a government ban on marching to deliver a petition to the National Assembly in Phnom Penh, demanding a higher minimum wage and more freedom of assembly.
The marchers, holding a forest of banners, filled a street a short distance from the parliament complex and advanced noisily until they were stopped by a barricade and lines of police, holding batons, shields and guns capable of firing gas canisters. A standoff of several hours was resolved when a representative from the Assembly came out and accepted the petition.
The workers were from the Coalition of Cambodian Apparel Workers Democratic Union. Among their demands was increasing the minimum wage from $153 to $208 per month. The clothing and footwear industry is Cambodia's biggest export earner.
The major Cambodian labor unions traditionally have been loosely allied with opposition parties, posing a potential political threat to longtime authoritarian leader Hun Sen.
Several thousand protesters gathered outside Greece's parliament, and unions braced for more austerity measures imposed by bailout lenders.
Two large union-organized rallies are planned in Athens on the holiday, with employees at many public services nominally on strike.
As the marches began, government officials prepared for more talks at a central Athens hotel with representatives of bailout creditors as the two sides were near an agreement to maintain draconian spending controls beyond the current rescue program.
The talks had been expected to end Sunday. Future spending cuts will include additional pension cuts and tax increases for Greeks, already hit by seven years of harsh cuts.
Greece's largest labor union, the GSEE, has called a general strike for May 17 to protest the latest austerity package.
A few thousand left-wing activists and laborers marched and held noisy rallies to press for higher wages and an end to temporary contractual jobs that deprive workers of many benefits. In sweltering summer heat, the crowds in Manila also protested alleged extrajudicial killings under President Rodrigo Duterte's drug crackdown.
The activists carried murals of Duterte and President Donald Trump, asking the Philippine leader to stay away from the U.S. president, who has invited Duterte for a U.S. visit. Protest leader Venzer Crisostomo fears an "America First" policy would be disadvantageous to poorer countries like the Philippines. "We would not want Duterte to be in cahoots with Donald Trump in oppressing the country and in implementing policies."
In Taipei, thousands of Taiwanese workers hoisted cardboard signs and banners in a march protesting what they said were unfairly low wages and deteriorating work conditions. A number of them staged a fake funeral procession, carrying a coffin with the words "basic annual pension" written on it, while others waved black flags.
Huang Yu-kai, president of the labor union of the Taiwan High-Speed Rail Corp. and a train conductor, said low wages in Taiwan are "the root of all problems."
"This is why we take part in this march every year," Huang said.
President Tsai Ing-wen said in a post on her Facebook page that improvements are being made even if major changes would take time. "Although reform would not be completed in one step, the progress we have made is not small."
Thousands of garment industry workers in the impoverished South Asian nation gathered to demand better wages and legal protection.
About 4 million people are employed in the country's garment industry, the second largest in the world. The industry, with about 4,000 factories, earns $25 billion a year from exports, mainly to the United States and Europe, but working conditions often are grim.
Lovely Yesmin, president of the Readymade Garments Workers Federation, one of several unions representing factory workers, said just increasing salaries is not enough.
She said workers must be provided better living quarters and health benefits, and factories must make provisions so the children of factory workers can be educated.
"These are our demands on the great May Day of 2017," she said.