DUBAI: Two Shiites were killed in overnight clashes with police in the eastern Saudi province of Qatif following the arrest of a prominent Shiite cleric and government critic, activists said on Monday.

Akhbar Shakuri and Mohammed Filfel died and a dozen other protesters were wounded during the clashes that erupted when police opened fire to disperse a demonstration against the arrest of Sheikh Nimr al-Nimr, said the activists.

The violence occurred in Riyadh Street, the main artery of Qatif city, they said. The reports could not be independently verified.

The interior ministry described Nimr as an “instigator of sedition” as it announced that he was arrested at Al-Awamiya in Eastern Province on Sunday, after being wounded in the leg while putting up resistance.

He was transferred to hospital and was due to be interrogated, ministry spokesman Mansur Turki said, cited by the official SPA news agency.

The new deaths bring to nine the number of people killed in clashes between Saudi authorities and protesters in the Shiite-populated region.

Nimr is considered one of the main advocates of demonstrations that first took place in February 2011 after an outbreak of violence between Shiite pilgrims and religious police in the holy city of Medina.

The protests escalated after the kingdom led a force of Gulf troops into neighbouring Bahrain to help crush a month-long Shiite-led uprising against the country's Sunni monarchy.

Most of Saudi Arabia's estimated two million Shiites live in the east, where the vast majority of the OPEC kingpin's huge oil reserves lie. Saudi Shiites complain of marginalisation in the kingdom.