WASHINGTON, USA: Amnesty International is calling for the immediate release of eight prominent Bahraini opposition activists arrested following a violent dispersal of demonstrators in Manama.

The eight activists, mainly leading members of Shi'a opposition groups prominent in the ongoing protests for reform, were arrested yesterday in armed raids on their homes by a joint force of Bahraini and Saudi Arabian security forces.

The security forces did not produce arrest warrants and the authorities have not revealed where the detainees have been taken, or allowed them access to lawyers or their families.

On Wednesday, the day before the arrests, at least six people were killed in Manama when Bahraini security forces, backed by Saudi Arabian troops, forcibly dispersed protestors who had set up camp at the city's Pearl Roundabout. At least one member of the security forces was killed but the majority were protestors.

The Bahraini authorities' increasing use of violence and intimidation against peaceful protesters and activists is totally unacceptable said Malcolm Smart, Amnesty International's Director for the Middle East and North Africa.

The authorities appear to be intent on shifting the blame to these opposition leaders for the violence meted out by the security forces. Instead, they should be conducting an immediate independent investigation into their forces use of excessive force, and bringing to justice those responsible for the serious abuses that we have seen in recent weeks.

A relative of Shi'a opposition activist Dr Abdel-Jalil al-Singace told Amnesty International that security forces smashed in the door of the house yesterday morning, stormed in and seized Dr al-Singace from his bedroom. A computer and mobile phone were also taken. The family was not given a reason for his arrest, and not told where he was taken.

The other activists arrested were Hassan Mshaima', a prominent colleagues of Dr al-Singace in al-Haq, a Shi'a opposition political association; Ibrahim Sharif, secretary general of the secularist opposition group Wa'ad; Abdel-Wahab Hussain, president of al-Wafa' Islamic Movement; Shi'a opposition activists Sa'eed al-Nuri, Abdel-Hadi al-Mukhodher and Hassan al-Haddad; and Dr Ali al-Ekri, a physician and one of the protest organisers.

Dr Ali al-Ekri works at al-Salmaniya hospital in Manama, which is currently surrounded by troops reportedly making access to the hospital difficult.

These eight detainees are all prisoners of conscience and should be immediately and unconditionally released said Malcolm Smart.

Amnesty International has grave fears for the detainees' safety, as several of them have previously alleged torture and mistreatment when they were previously detained in 2010.

Dr al-Singace, Sa'eed al-Nuri, Abdel Hadi al-Mukhodher and Hassan al-Haddad were held from August 2010 until the end of February 2011 when they were released on the orders of the King as a response to popular calls for reform.

Hassan Mshaima' had only recently returned from exile to Bahrain.

The arrests follow rising tension and violence in Bahrain. This week at least nine people have been killed in clashes between protesters and Bahraini and Saudi Arabian security forces. Security forces have been deployed in many parts of Manama, especially in predominantly Shi'a neighbourhoods and villages close to the capital.