Tens of thousands of people across the globe were hitting the streets Thursday for mass rallies marking International Labour Day, with Turkey a potential flashpoint on the anniversary of clashes that spawned a nationwide protest movement.

In tense Istanbul, thousands were expected to gather at the highly symbolic Taksim Square in defiance of government orders to stay away -- with a massive police presence on the streets a year after violent May Day demonstrations snowballed into a huge anti-government movement.

Rallies were also set to take place across Asia, including in Hong Kong, Jakarta, Kuala Lumpur, Singapore, Taipei and Seoul, where the annual protest was expected to take a sombre tone in the wake of the South Korean ferry disaster.

Russian workers, meanwhile, were to parade on Red Square for the first time since 1991 -- the latest Soviet tradition to be revived as a wave of patriotism sweeps the country.

May Day was a key date in the Soviet calendar, with elaborate celebrations involving ranks of marching athletes, soldiers and workers on the Moscow square, but in recent years the annual demonstrations have been relegated to a city highway.

In Cambodia, security forces armed with sticks and batons forcibly dispersed dozens of May Day protesters near Phnom Penh's Freedom Park, according to an AFP photographer.

Several people were beaten.

The park, opened by the government in 2010 as a designated area for people to air their grievances, was closed off by police with barbed wire as the authorities seek to clamp down on protests against long-ruling strongman premier Hun Sen.

"We are sad that we could not mark May Day properly. Workers' rights have been thwarted," said Ath Thorn, president of the Coalition of Cambodian Apparel Workers Democratic Union.

Indonesian police said some 33,000 workers were set to rally across the capital Jakarta. Unions said up to two million workers would be out in force to demand better working conditions in Southeast Asia's most populous nation, although in previous years the numbers have come in much lower than such forecasts.

"Demonstrations will be held nationwide but the biggest will be in Jakarta, with around 33,000 workers," police spokesman Rikwanto told AFP, adding that 18,000 police officers would be out on the streets.

He said workers were planning further rallies on Friday, with some 10,000 protesters expected to turn out.

- Sombre Seoul protest -

In Hong Kong, union organisers said some 5,000 people were set to join their march from the city's Victoria Park to government headquarters, with better working hours top of the agenda.

Malaysian civil society groups said they expected several thousand people to attend a rally in Kuala Lumpur against price hikes implemented by the long-ruling government, which already is under domestic and international scrutiny over its handling of the passenger jet that disappeared on March 8.

The protest takes aim at price increases stemming from subsidy cuts as well as plans to introduce a general sales tax from next year. Opposition leader Anwar Ibrahim was due to participate.

Meanwhile in Taiwan, thousands of workers were set to march to the labour ministry demanding wage hikes and a ban on companies hiring cheap temporary or part-time workers.

In Seoul around 5,000 workers were expected to rally outside Seoul railway station in the afternoon but this year's traditional May Day trade union gathering has been overshadowed by the ferry disaster that has claimed the lives of hundreds of people, many of them schoolchildren.

The workers were to march to City Hall and pay their respects to the victims of the April 16 disaster at a temporary memorial.

In Singapore, critics of the government's manpower and immigration policies were scheduled to hold a rally in a designated protest park.

The police have warned the organisers, who have been accused of fanning xenophobia against foreign workers, against carrying out plans to deface a poster of Prime Minister Lee Hsien Loong as part of the protest.

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