Mohammed al-Qahtani, a member of the Saudi Civil and Political Rights Association, told CNN that security forces broke up a protest in front of the country's human rights commission in Riyadh. Several prisoners have remained behind bars without trial, he said.
"These are ongoing protests about political prisoners," he said. "The government is not willing to take them to court and issue verdicts."
CNN said it was unable to verify Qahtani's claims. The activist is on trial for running an unlicensed organization.
Calls by CNN to the Saudi Interior Minister went unanswered. The official Saudi Press Agency reports Wednesday the ruling monarch issued a decree reliving Interior Minister Ahmad bin Abdulaziz of his post. A royal decree, meanwhile, related to "amnesty for prisoners of public rights according to certain conditions," the official news agency reports.
Demonstrations in Saudi Arabia are exceptionally rare.