Qatif – Saudi police have surrounded several mosques across the country, including in the capital Riyadh, as activists begin a nationwide mosque sit-in.

Activists say the sit-ins were staged to demand the immediate release of thousands of political prisoners held by the regime without trial or legitimate charges.

Footage released by activists show heavy police presence in the capital and the city of Jeddah.

Saudis have named the sit-in the "Friday of Al-Ahmed" after a prominent cleric who was arrested several months ago.

They say the sit-in will continue until the Ministry of the Interior meets their demand and releases their loved ones and relatives.

Saudi activists say there are more than 30,000 political prisoners, mostly prisoners of conscience, in jails across the Kingdom.