DUBAI: Bahraini police have arrested prominent human rights blogger Zainab al-Khawaja, according to a rights group and video posted online of her being roughed up, handcuffed and dragged off into custody.

Khawaja had been taking part in a sit-in protest on a highway leading to the capital Manama when police moved in to detain her on Thursday, the Bahrain Center for Human Rights said in a statement.

Security forces fired tear gas and stun grenades to disperse the protest of hundreds of Bahrainis, while Khawaja, 27, and other women staged the sit-in on a roundabout, said the organization.

A daughter of imprisoned leading activist Abdulhadi al-Khawaja, she was seen sitting on the grass before police moved in to take her away, the video footage posted on YouTube showed.

But while all other women fled the scene, Khawaja remained sitting in the middle of the roundabout.

The footage showed her being handcuffed by a female policewoman.

Another female security woman appears to grab Khawajah's face violently, before both dragged her with the handcuffs to a police vehicle.

One of the policewomen can be seen in the footage punching Khawaja in the chest as she lay on her back on the pavement.

In its statement, the Bahrain Center for Human Rights called for action to "guarantee her release and protection from further physical violence."

Sunni-ruled Bahrain's security forces used live ammunition and heavy handed tactics to crush mass Shiite-led democracy protests earlier this year.

A report by the Bahrain Independent Commission of Inquiry said last month it found police used "excessive force" and tortured detainees in a crackdown on the protests, and made a series of recommendations.

The report published on November 23 said the death toll from the unrest was 35, including five security personnel and five detainees who were tortured to death while in custody. Hundreds were also injured.

The findings, which studied events in February and March, said that 11 other people were killed later. The commission concluded that a total of 2,929 people were detained during the protest movement, and at least 700 remain in prison.

Bahrain's King Hamad vowed sweeping reforms and set up a National Commission to follow up on the recommendations made by the panel.