Riot police in Turkey have clashed with labor activists trying to gather in Istanbul's Taksim square to celebrate May Day.

Police used clubs, tear gas and water cannons on Thursday to disperse workers in different areas of the city.

Authorities had warned they would use force to prevent the rallies, which have been banned since 1977.

Media reports said more than 30,000 security personnel were on duty to enforce the ban.

Police wearing gas masks first broke up a crowd that had gathered in front of a labor union office with the intention of walking to Taksim square, where at least 34 demonstrators were killed on May 1, 1977.

The workers then ran into the building and police blockaded it, preventing them from leaving.

'Extremist' unrest

Police, blocking all streets leading to Taksim, also broke up groups of workers trying to enter the square through various entrances, firing tear gas and beating some demonstrators with clubs.

Roughly half a million union members were expected to try to march on Thursday.

Negotiations were reportedly under way between police and unions to try to seek a compromise.

Officials said they had intelligence that groups of extremists would seek to provoke unrest during the march.

Turkey's Anatolia news agency reported that a man in possession of 17 molotov cocktails was arrested near Taksim.

Workers' rights

The first of May is marked annually in many countries as a day of labor recognition.

Human Rights Watch (HRW), a New York-based rights group, used the day to call on Lebanese authorities and employers to improve treatment of domestic workers.

HRW's Nadim Houry said: "On the eve of Lebanese Labor Day, we would like to highlight a huge segment of laborers who are not recognized as such.

"They are domestic workers, almost a 100 per cent of whom are foreigners."

Workers and activists in the Philippines on Thursday called for a wage increase amid soaring food prices.

While in Greece, disruptions to public transport services and domestic flights were expected due to trade union strikes.

Thousands of people were expected to turn out in Havana to hear Raul Castro, Cuba's president, give his first May Day address.

Overnight, police in the German city of Hamburg arrested several rioters after pre-May Day street protests turned violent.

PHOTO CAPTION 

Turkish riot police fire tear gas at demonstrators during a May Day rally in Istanbul, Turkey, Thursday, May 1, 2008.

Al-Jazeera