Iran has demanded the release of seven of its nationals who were abducted last month in restive Syria, media reported Tuesday.

"According to the last information we have, they are in good health and we are trying to obtain their release," foreign ministry spokesman Ramin Mehmanparast was quoted as saying.

The seven are said to be engineers or technicians working on an electricity power plant in Jandar, close to the city of Homs, which has become one of the flashpoints in the Syrian uprising against the regime of President Bashar al-Assad.

An unknown group calling itself the "Movement Against the Expansion of Shiism in Syria" on Monday claimed responsibility for their abduction in a statement received by AFP in Nicosia.

The group said it had sent demands to the Iranian embassy in Damascus last week that have to be met for the hostages to be released.

It said it was opposed to Iran's support of the Syrian government and of the Hezbollah militia in neighbouring Lebanon.

Iran, a predominantly Shiite country, is the main ally of Syria, whose regime is controlled by the Shiite minority Alawite branch while most of the country is Sunni.

Iranian officials have not spoken of the abductors.

The kidnapped Iranians' employer, the Iran Power Plant Projects Management Company, or Mapna, on Tuesday said the families and colleagues of the men were worried.

Its public relations director, Behnam Haghighi, called on "international bodies" to help with the men's release, according to the official news agency IRNA.

Five of Mapna's employees were initially abducted. The other two were taken when they went to investigate their colleagues' disappearance.