Hundreds of people demonstrated in Riyadh Tuesday to denounce detentions of dissidents following a call from an exiled opposition group.
The official Saudi Press Agency (SPA) downplayed the protest, descrbing it as "a rally by a number of individuals" which "disrupted traffic" in a busy district of the Saudi capital.
But, anti-riot police intervened to disperse the protesters who gathered outside the Kingdom Tower on the main Al-Ulaya thoroughfare after the London-based Movement for Islamic Reform called for the rally against the arrest of political opponents to the ruling Saud family, AFP said.
Witnesses said police detained a number of protesters, mostly youngsters who chanted "Allahu Akbar" (God is greatest). One of those arrested said many of the people detained were released after a few hours.
AFP reported dozens of people, including women, tried to gather near the area of the main rally after they were dispersed by police.
The scene was repeated several times until the protest ended around three hours later at about 6:30 pm (1530 GMT).
The opposition group timed the protest to coincide with a human rights conference that opened in Riyadh Monday, the first such gathering in Saudi Arabia.