Omar al-Saeed is the fourth member of the Saudi Civil and Political Rights Association (ACPRA) to be jailed this year after the group issued statements attacking the ruling family over its human rights record and calling for democracy.
Saeed did not have legal representation at the secret hearing when he was sentenced, ACPRA said in a statement on its website.
"It's just another troubling instance of Saudi authorities' absolute refusal to countenance any activism or criticism of Saudi policies or human rights abuses," said Adam Coogle, Middle East researcher at Human Rights Watch.
A spokesman for the Justice Ministry said he could not comment on the report or confirm its accuracy.
U.S.-allied Saudi Arabia is ruled by the al-Saud family together with powerful clerics from the country's ultra-conservative Wahhabi school of Sunni Islam. » | Reporting by Angus McDowall; Editing by Sonya Hepinstall | Riyadh | Sunday, December 05, 2013