Algerian Prime Minister Abdel Malek Sellal said here on Monday that 36 foreign hostages from eight countries along with an Algerian worker were killed, and another five remain missing in the hostage crisis at a gas facility in the country's southeast.

Sellal told a press conference held in Algiers that seven of the killed have not been identified yet.

He added that there were 790 workers, including 134 foreigners from 26 countries, were in the gas plant complex in Illizi province when the attack took place Wednesday, and most of them were rescued while five foreigners are still missing.

Meanwhile, 29 militants were killed and three others arrested during the rescue operation launched by the Algerian army's special forces, the prime minister pointed out.

He went on saying that the attack, which was plotted two months ago by an armed group, was "coward and carried out by a group of terrorists and mercenaries, as the majority of whom were foreigners."

The armed group was composed of 32 militants with eight nationalities, including 11 Tunisians and two Canadians, while the rest from Niger, Mali, Mauritania, Libya, Egypt, and Yemen, he continued, adding that the group is led by an Algerian militant called Ben Cheneb Mohamed Amine and assisted by Abubakr al-Masri.

The main target of this assault was to abduct a group of Western workers and take them to northern Mali and swap them with ransoms, Sellal introduced.

Meanwhile, the prime minister defended the Algeria's decision to open its airspace to French jet fighters to go to the north of Mali and fight armed groups there.

"Algeria's decision to open its airspace is a sovereign decision, and has a connection with the UN resolution related to the military intervention in Mali, which requests the neighboring nations to cooperate in its implementation," he said.

As for whether Algeria would send troops to Mali to fight terrorists there, Sellal said the Algerian Constitution " stipulates that the National Army shall never be sent to fight beyond borders," adding that "It is a doctrine which cannot be changed."