A SAUDI judge has sentenced to death a prominent cleric who had called for greater rights for the kingdom's Shi'ites, the cleric's brother said.

Sheikh Nimr al Nimr was detained in July 2012 following demonstrations that erupted in February 2011 in Qatif district, home to many of the Sunni-ruled country's Shi'ite minority.

His arrest prompted ­dead-ly protests in the oil-producing east of the country.

Mohammed al Nimr,the cleric's brother, reported the death sentence on his Twitter account.

It could raise tensions in Qatif, which has historically been the focal point of anti-government demonstrations demanding an end to dis-crimination, but where the frequency of protests has died down over the past year.

A prosecutor said last year he was seeking to convict Nimr for "aiding terrorists". Former interior minister Prince Ahmed bin Abdulaziz has accused Nimr of being "mentally unbalanced".

His capture, during which he was shot and wounded by police, prompted several days of protests in which three people were killed.

Protests continued spo-radically in Qatif, where more than 20 people have died in violence, until 2013.

Nimr has become the most prominent cleric calling for more rights for the Shi'ite minority and is accused by the government of helping to instigate the unrest which broke out during the Arab uprisings.