Saudi authorities have jailed a lawyer a day after he criticised the arrest of several top intellectuals in a television interview, sources say.
The last six months have seen rare displays of dissent
Abderrahman al-Lahem was reportedly jailed after expressing his surprise on Arab television station al-Jazeera.
It emerged on Tuesday that a number of leading Saudi activists - some liberal, others Islamist - had been arrested.
The detained intellectuals had put their names to a petition calling for a constitutional monarchy.
The exact number of intellectuals arrested remains in doubt, but is thought to be between five and 12.
Three of those arrested have since been released, human rights activist Ibrahim al-Mugaiteeb told the Associated Press news agency.
The Human Rights First pressure group, headed by Mr Mugaiteeb, said the detentions contradicted recent efforts towards reform undertaken by Saudi rulers.
The group called for all the detainees to be released.
It also expressed surprise that the National Human Rights Association - a newly-created government-backed pressure group - had remained silent on the arrests.
Mr Mugaiteeb said the arrested men had been planning a statement criticising the government-approved rights body and calling for the establishment of a new group independent from the state.
The US State Department has also criticised the arrest of the intellectuals.
"It's inconsistent with the kind of forward progress that reform-minded people are looking for," said spokesman Adam Ereli.
Since the attacks of the 11 September 2001, Saudi Arabia has been under US pressure to take tougher action against extremism and intolerance.