Witnesses in Bahrain say riot police used water cannons and tear gas to disperse hundreds of anti-government protesters trying to reach a heavily guarded site that was once the hub of their uprising.

The demonstrators marched toward Pearl Square in Bahrain's capital Manama on Friday after a funeral procession for a protester who died in custody. The government says the man died of a blood disease.

The witnesses spoke on condition of anonymity fearing for their own safety.

Demonstrators hurled firebombs and rocks at troops about 700 meters (yards) from Pearl Square, where crowds gathered in February 2011 as the Arab Spring-inspired uprising erupted in the Gulf nation.

Bahrain's majority Shiites seek greater rights in the Sunni-ruled kingdom. At least 50 people have died in nearly 20 months of unrest.