Tanks, teargas and helicopters have been used by Bahraini security forces to disperse hundreds of pro-democracy demonstrators in the capital, Manama.
At least five people – two demonstrators and three policemen – have been killed.
Bahrain’s youth movement, which had been leading protests, have called for a mass demonstration
An opposition politician earlier said five protestors were killed in clashes with police.
A third policeman died after he and two colleagues were struck by cars driven at high speed by demonstrators.
The violence came during a security operation to move thousands of anti-government demonstrators camped out in Manama’s central Pearl Square.
Local hospitals say that dozens have been injured.