Bahrain arrested several opposition leaders on Thursday as part of a crackdown on anti-government protests in the Gulf kingdom, driven by majority Shiites, who are calling for democracy and civil rights.

Five hardline Shiite activists and one Sunni were rounded up during the night, a parliamentarian from the Shiite opposition alliance told AFP.

They were arrested in the night, Al-Wefaq deputy leader Khalil Marzouk told AFP.

US Secretary of State Hillary Clinton has said she finds the situation in Bahrain alarming and criticised the government's use of force against protesters. She said Bahrain and Gulf allies were on the wrong track and urged the tiny Gulf kingdom to negotiate a political agreement with demonstrators.

We find what's happening in Bahrain alarming. We think that there is no security answer to the aspirations and demands of the demonstrators, she told CBS. They are on the wrong track.

The US State Department also released a message on twitter, saying We object to excessive force and violence against demonstrators; we raised our concerns directly today to Bahrain.