At least 40 Bahraini prisoners have been hurt after security forces used batons, tear gas, pepper spray and stun grenades against inmates protesting over their conditions, an activist said.

Sayed al Muhafada of the Bahrain Centre for Human Rights said he had received a call from inside the prison telling him that around 100 prisoners were protesting over being deprived of family visits and other grievances.

The Interior Ministry said security forces “restored order” after a number of detainees rioted on Friday. "They tried to break the doors, the police interfered and restored order," a tweet by the ministry claimed.

Bahraini government has been broadly criticized by international organizations for its widespread violations of human rights.

The small Persian Gulf Arab state and Western ally, which hosts the US Fifth Fleet, has been rocked by bouts of unrest since February 2011 when an uprising led by members of the Shia majority demanded the Sunni al-Khalifa dynasty give up power.

The authorities crushed the revolt but protests and clashes have persisted despite continuing talks between government and opposition.

At least 80 people have been killed since Arab Spring-inspired protests erupted in Bahrain in early 2011, according to the International Federation for Human Rights.

NTJ/SHI