BERLIN -- Left-wing groups and trade unions were staging rallies around the world Friday to mark International Workers Day.

Most events were peaceful protests for workers' rights and world peace. But May 1 regularly sees clashes between police and militant groups in some cities.

International Workers Day originates in the United States. American unions first called for the introduction of an eight-hour working day in the second half of the 19th century. A general strike was declared to press these demands, starting May 1, 1886. The idea spread to other countries and since then workers around the world have held protests on May 1 every year, although the U.S. celebrates Labor Day on the first Monday in September.

Here's a look at some of the May Day events around the world:

May Day protests in Turkey

TURKEY

Police and May Day demonstrators clashed in Istanbul as crowds determined to defy a government ban tried to march to the city's iconic Taksim Square.

Security forces pushed back demonstrators using water cannons and tear gas. Protesters retaliated by throwing stones and hurling firecrackers at police.

Authorities have blocked the square that is symbolic as the centre of protests in which 34 people were killed in 1977.

Turkish newswires say that 10,000 police officers were stationed around the square Friday.

The demonstrations are the first large-scale protests since the government passed a security bill this year giving police expanded powers to crack down on protesters.

May Day protesters in South Korea

SOUTH KOREA

Thousands of people marched in the capital Seoul on Friday for a third week to protest government labour policies and the handling of a ferry disaster that killed more than 300 people a year ago.

Demonstrators occupied several downtown streets and sporadically clashed with police officers. Protesters tried to move buses used to block their progress. Police responded by spraying tear gas. There were no immediate reports of injuries.

South Korean labour groups have been denouncing a series of government policies they believe will reduce wages, job security and retirement benefits for state employees.

May Day in the Philippines

PHILIPPINES

More than 10,000 workers and activists marched in Manila and burned an effigy of Philippine President Benigno Aquino III to protest low wages and a law allowing employers to hire labourers for less than six months to avoid giving benefits received by regular workers.

Workers in metropolitan Manila now receive 481 pesos ($10.80) in daily minimum wage after a 15 peso ($0.34) increase in March.

Although it is the highest rate in the country, it is still "a far cry from being decent," says Lito Ustarez, vice chairman of the left-wing May One Movement.

May Day protests in Greece

GREECE

In financially struggling Greece, an estimated 13,000 people took part in three separate May Day marches in Athens, carrying banners and shouting anti-austerity slogans. Minor clashes broke out at the end of the peaceful marches, when a handful of hooded youths threw a petrol bomb at riot police. No injuries or arrests were reported.

Earlier, ministers from the governing radical left Syriza party joined protesters gathering for the marches, including Finance Minister Yanis Varoufakis -- who was mobbed by media and admirers -- and the ministers of labour and energy.

May Day protests in Germany

GERMANY

Police in Berlin say the traditional 'Walpurgis Night' protest marking the eve of May 1 was calmer than previous years.

Several thousand people took part in anti-capitalist street parties in the north of the city. Fireworks and stones were thrown at police, injuring one officer. Fifteen people were detained. Elsewhere in the German capital revelers partied "extremely peacefully," police noted on Friday morning.

At noon, Green Party activists unveiled a statue at Alexanderplatz in central Berlin of Edward Snowden, Julian Assange and Chelsea Manning, considered heroes by many on the left for leaking secret U.S. intelligence and military documents. The statue, called "Anything to say," depicts the three standing on chairs and is scheduled to go on tour around the world, according to the website http://www.anythingtosay.com/.

In the central German city of Weimar far-right extremists attacked a union event. Police said 15 people were injured and 29 were arrested.

May Day marked in Russia

RUSSIA

In Moscow, tens of thousands of workers braved chilly rain to march across Red Square. Instead of the red flags with the Communist hammer and sickle used in Soviet times, they waved the blue flags of the dominant Kremlin party and the Russian tricolour.

Despite an economic crisis that is squeezing the working class, there was little if any criticism of President Vladimir Putin or his government.

The Communist Party later held a separate march under the slogan "against fascism and in support of Donbass," with participants calling for greater support for the separatists fighting the Ukrainian army in the Donbass region of eastern Ukraine.

May Day marked in Italy

ITALY

In Milan, police released water from hydrants against hundreds of demonstrators, many of them scrawling graffiti on walls or holding smoky flares during a march in the city, where the Italian premier and other VIPs were inaugurating Expo, a world's fair that runs for six months.

Italian labour confederation leaders held their main rally in a Sicilian town, Pozzallo, where thousands of migrants from Africa, the Middle East and Asia have arrived in recent weeks after being rescued at sea from smugglers boats. Hoping to settle for the most part in northern Europe, the migrants are fleeing poverty as well as persecution or violent conflicts in their homelands.

May Day marked in Spain

SPAIN

Around 10,000 protesters gathered under sunny skies in Madrid to take part in a May Day march under a banner saying "This is not the way to come out of the financial crisis."

Spain's economy is slowly emerging from the double-dip recession it hit at the end of 2013, but the country is still saddled with a staggering 23.8 per cent unemployment rate.

"There should be many more of us here," said demonstrator Leandro Pulido Arroyo, 60. "There are six million people unemployed in Spain, and many others who are semi-unemployed, who although they may be working don't earn enough to pay for decent food."

POLAND

Rallies in Warsaw were muted this year after Poland's weakened left wing opposition held no May Day parade.

Only a few hundred supporters of the Democratic Left Alliance, or SLD, and of its ally, the All-Poland Trade Union, gathered for a downtown rally Friday to demand more jobs and job security.

Cubans march on May Day

CUBA

Thousands of people were converging on Havana's Plaza of the Revolution for the traditional march, led this year by President Raul Castro and Venezuelan President Nicolas Maduro. After attending Cuba's celebration, Maduro was to fly back to Caracas to attend the May Day observances in his own country.

Additional marches were planned in major cities around Cuba, including Santiago and Holguin in the east.