Turkish police have detained more than 80 people and used tear gas to prevent thousands of leftist protesters from marching to Istanbul's Taksim square to hold a May Day rally.

Authorities declared the square off-limits to protesters, but allowed a small number of trade union leaders to lay flowers at the square to mark the day.

Officials had shut down schools in the area for the day for fear of violence.

Members of leftist groups often clash with police during May Day observances in Turkey.

In 1977, a May Day rally at Taksim square turned violent when unidentified gunmen opened fire on a crowd of demonstrators. Thirty-seven people were killed in that incident.

Some information for this report was provided by AFP and AP.