Westerners among those reported dead

Algeria raided a remote Sahara gas plant and killed 34 hostages, some of them Westerners, and 15 of their Islamist kidnappers at a desert gas field on Thursday, the Mauritanian news agency ANI quoted a spokesman for the kidnappers as saying.

"Thirty-four hostages and 15 kidnappers were killed in a raid by the Algerian army," the spokesman said in remarks that have not been independently confirmed.

The source said Westerners were among the dead, but did not elaborate.

The militants said the gas plant attack came in retaliation for Algeria allowing France to use its airspace to attack al-Qaida-linked rebel groups in neighboring Mali.

The three countries, which have citizens among the hostages at the BP-operated In Amenas gas field, said they had received confirmation of the operation from Algerian authorities.

"We can confirm that we have been informed of a military operation against the In Amenas complex," Norwegian Foreign Ministry spokesman Kjetil Elsebutangen said.

Britain's Foreign Office and a French government source also said they had been informed of an assault.

British Prime Minister David Cameron's spokesman said earlier on Thursday that Britain would consider any requests for help from Algeria in its efforts to free the hostages.

Kidnappers with the Masked Brigade, who have been speaking through a Mauritanian news outlet, said the Algerians opened fire as the militants tried to leave the energy complex with their hostages a day after seizing the installation deep in the desert.

The militant spokesman said the leader of the kidnappers, Abou El Baraa, was among those killed. He said the militants would blow up the remaining hostages if the Algerian army approached.