ALGIERS - At least 12 hostages were killed during Algerian forces' rescue operation at a gas field facility in the southern province of Illizi, official APS news agency reported Friday.

Citing a government source, APS said both Algerian and foreign workers are among the killed, without specifying the foreigners' nationalities.

Earlier on Friday, APS said that 18 militants, who took part in attacking the gas plant and kidnapping its workers, had been killed during the raid.

Local Ennahar television said that the killed militants include a French, a Malian, a Tunisian, two Egyptians, two Libyans and several Algerians.

On Thursday, Algerian Interior Minister Daho Ould Kablia indicated that the number of militants who attacked the gas field was around 20. "The militants came on three 4x4 vehicles, which can carry some 20 people."

Algerian forces on Thursday launched the raid on the gas field compound and some 650 hostages had been freed, including 570 Algerians and more than half of the 132 detained foreigners, APS said Friday, citing a security source.

The source said that the army's special forces are still looking for a peaceful solution to free the rest hostages, before having to eradicate the militants who take refuge in a refinery of the gas field facility.

According to the source, the gas facility has been shut down in view of any explosion risk.

Local media reported Friday that US and British planes had arrived in Algeria to take home their nationals.

Meanwhile, a number of injured workers have been evacuated to Azhar clinic in Algiers' southwestern Dely Brahim suburb.