“We were heading to Rusayl (district of Muscat) when a group of masked men waylaid us. They came in two vehicles — one was a saloon taxi and the other was a van,” Saeed Al-Hashmi was quoted as saying in the English-language Times of Oman.

He said he and colleague Basma Al Rajhia were roughed up in a remote area before being released.

Hashmi said his head was covered and his hands and legs bound before he was beaten up.

“The group threatened me saying that they will kill me if I participate in such activities in the future,” he said.

The two are being treated at a government hospital in Muscat, Times of Oman said, adding that police were investigating the case.

The activists have taken part in an on-going sit-in by the Oman Council, an advisory body in Muscat to demand political, social and economic reforms.

Interior Ministry were not available to comment.

Oman broke up a month-long protest in the industrial city of Sohar this month, detaining dozens, activists said. At least one person was killed in clashes with police in Sohar in February and another was killed this month.

Sultan Qaboos bin Said has promised reforms since protests began.

He promised in March to cede some legislative powers to the partially elected Oman Council. At present, only the sultan and his cabinet can legislate and a transfer of powers has yet to be announced.

The sultan also raised civil service pay and pensions of government employees and doubled social security allowances.

Protesters are still staging sit-ins in Muscat for better pay and benefits in the private sector.