KUWAIT CITY: A Gulf rights group has strongly condemned heavy jail terms against two prominent Saudi rights activists and called on the authorities in the kingdom to free them immediately.

"We strongly condemn these jail terms and demand that Saudi authorities release them immediately and scrap the verdicts," said the Gulf Forum for Civil Societies (GFCS), a pan-Gulf liberal group, in a statement overnight.

"We caution against the use of the judiciary as a means of settling political scores, which has become a policy used repeatedly by Gulf states during the past two years," the forum said.

The criminal court in Riyadh on Saturday sentenced activists Mohammed al-Gahtani and Abdullah al-Hamed to 10-year and five-year jail terms respectively.

Gahtani is an official with the independent Saudi Association of Civil and Political Rights (ACPRA). The court also ordered the group's dissolution for "failing to obtain authorisation."

The two activists were convicted of violating a law on cybercriminality by using Twitter to denounce various aspects of political and social life in the ultra-conservative kingdom. They now have 30 days to appeal.

The two men reacted calmly to the verdict, saying they planned to continue their "peaceful struggle."

The GFCS said it held the Saudi authorities responsible for the "physical and psychological safety" of the two activists, and called on international rights groups to apply pressure on Riyadh to free them.

Gahtani said in June last year that he had been accused of "spreading sedition" and "rebelling against the authority" of the king.

The Saudi group claims to have created a file listing "hundreds of human rights violations over the past two years," and says the kingdom is holding around 30,000 political prisoners.