Black smoke is seen from Homs refinery
lack smoke is seen from Homs refinery December 8, 2011 in this handout released by Syria's national news agency SANA.

Iran said on Wednesday that five Iranian technicians working in Syria have been abducted by an unidentified group, and called for their immediate release.

Five Iranian technicians working on a power plant project have been kidnapped in the Syrian city of Homs, the semi-official Mehr news agency announced on Wednesday, reading a statement from the Iranian embassy in Damascus.

"The five were kidnapped on Wednesday at 0630 a.m. while heading to their work place ... We demand their immediate release," Mehr quoted the statement as saying.

Meanwhile Syria's state news agency SANA reported that eight engineers "of different nationalities" had disappeared. They had taken a bus to go to their work at a power plant in Homs province.

Homs is the centre of anti-government protests and activists say the city has been besieged by the security forces for several weeks.

Despite international condemnation of the Syrian regime crackdown on protesters, Iran remains a strong ally of Assad.

The country has however welcome the leader's decision to allow foreign monitors in Syria after it signed an agreement with the Arab League that aims at stopping the bloodshed.