The whereabouts of the detainees, reportedly nabbed on Wednesday, are still unknown.

The protests were held despite a strict ban by the Saudi regime on anti-government rallies.

Saudi Arabia has been the scene of frequent protests since early 2011. Over a dozen demonstrators have been killed and many arrested in the regime's crackdown during the past two years.

Saudi activists say there are more than 40,000 political prisoners, mostly prisoners of conscience, in jails across the Kingdom.

According to the activists, most of the detained political thinkers are being held by the government without trial or legitimate charges and have been arrested for merely looking suspicious.

Some of the detainees are reported to be held without trial for more than 16 years. Attempting to incite the public against the government and the allegiance to foreign entities are usually the ready-made charges against political dissidents.

In Saudi Arabia, protests and political gatherings of any kind are prohibited.