The daughter of a prominent Bahraini opposition activist and 40 other people were arrested yesterday, hours after security forces used tear gas to disperse hundreds of protesters demanding political reforms.

At least 45 people were injured in the security-forces operation to break up the three separate protests across the Gulf Arab island kingdom late on Thursday, activists said.

Bahrain crushed an uprising led by majority Shi'ite Muslims last year, after successful popular revolts in Tunisia and Egypt, but protest marches and rallies continue.

Bahraini Shi'ites say they have long been marginalised in political and economic life, which the Government denies. Bahrain's Sunni rulers have rejected the main opposition demand – an elected parliament with full powers to pass laws and form governments.

The head of the Bahrain Youth Society for Human Rights, Mohammed al Maskati, said Zainab al Khawaja was arrested when she tried to hold a solitary protest sit-in at al Badei street close to the capital Manama.

Zainab is the daughter of Abdulhadi al Khawaja, a leading Shi'ite figure in the uprising who ended more than three months of hunger strike in May after drawing attention to the issue of imprisoned activists.

Government officials were not immediately available for comment.