Oman's Supreme Court has ordered a retrial of 11 democracy activists convicted of forming an illegal gathering, their lawyer said on Monday, after they staged a prison hunger strike last month.

They were jailed last year in a security crackdown after protests in the Sultanate inspired by Arab Spring uprisings elsewhere in the region.

"The Supreme Court ordered the appeals court to review the case of the 11 prisoners who have been jailed for illegal gathering," said the lawyer, Khalifa al-Hinai. "It is a victory and we hope there will be a dismissal after the review."

No date has been set for the retrial, he said.

The 11 activists and 10 others went on hunger strike at Samail prison in northwest Oman for several days in February demanding to be released on the grounds that their imprisonment was unlawful.

The other 10 are serving jail terms of up to 18 months for slandering the country's ruler, Sultan Qaboos. It was not immediately clear if their case would be heard by the Supreme Court.

The 11 men whose case was heard on Monday were also sentenced to up to 18 months, for protesting over unemployment and state corruption. A higher court had earlier turned down their requests for an appeal.

Oman, which sits astride the Strait of Hormuz where some 40 per cent of the world's sea-borne oil exports pass, sought to placate demonstrators by pledging to create tens of thousands of public sector jobs.

But delays in implementing the promises have kept the protests simmering and some popular anger was directed against the sultan. - Reuters