Saudi authorities have freed all but two of a group of women arrested early this month while staging a sit-in to demand the release of Islamist prisoners in the city of Buraida, police said on Monday.

"All women arrested have been freed, with the exception of two of them who refused to leave even after all procedures for their release were completed," a police spokesman in the northern Qassim province said in a statement carried by the SPA news agency.

"Contacts are ongoing with their families to convince them to implement the judicial order," said the spokesman.

SPA had previously reported that Saudi police arrested 176 people on March 1 for holding a protest.

Authorities have accused the protesters of acting on behalf of "deviant groups" -- a term they usually use to refer to the Al-Qaeda jihadist network.

During a Thursday tour of Buraida, Qassim's main city, interior ministry spokesman Mansur al-Turki said that all prisoners had been released "with the exception of 19 women, 55 Saudis, and an Egyptian who had impersonated a Saudi."

Demonstrations are banned in Saudi Arabia, an ultra-conservative Muslim kingdom that has remained relatively untouched by the Arab Spring uprisings.

Small groups of women have gathered almost daily in Buraida, north of Riyadh, to demand the release of imprisoned Islamist relatives, and dozens of protesters held a rare sit-in outside the Buraida prison in September.

A wave of deadly Al-Qaeda attacks in the kingdom between 2003 and 2006 prompted the authorities to launch a crackdown on the local branch of slain Saudi-born Osama bin Laden's group.