In Bahrain, witnesses say riot police have tried to disperse protesters with tear gas and rubber bullets.
The clashes took place as officers attempted to stop people gathering for a major rally in the capital, Manama.
It follows demonstrations on Sunday, with protesters calling for reform in the island kingdom.
Bahrain has Sunni muslim rulers but the population is 70 per cent Shia, who claim they are regularly discriminated against.
Photos via Al Jazeera's Sara Hassan.