Islamist gunmen killed two people and took 41 Western hostages Wednesday in Algeria in what they said was a revenge attack on the country for opening its airspace to French warplanes hitting Islamists in Mali.
The Islamists, who said they entered Algeria from northern Mali, told Mauritanian media they were holding 41 Westerners including French, British and Japanese citizens, as well as seven Americans, at a southern gas field.
One Briton and an Algerian were killed in the attack, Algeria's Interior Minister Dahou Ould Kablia said. Six people were wounded: another Briton, a Norwegian and a Scot, as well as an Algerian security agent and two policemen.
Britain said it was working closely with Algeria over the crisis.
The In Amenas gas field is jointly operated by British oil giant BP, Norway's Statoil and state-run Algerian energy firm Sonatrach. Production was shut down after the attack.
A worker at the scene told AFP by phone that the armed group was demanding freedom for 100 Islamists held in Algeria in exchange for the Western hostages.
"The assailants have demanded that these Islamists be taken to northern Mali," he said.
A group calling itself "Signatories for Blood" claimed the action in a post to the Mauritanian website Alakhbar.
It was in retaliation both for the French intervention in Mali and for Algeria's cooperation, it said.
"Algeria was chosen for this operation to teach (Algerian President Abdelaziz) Bouteflika that we will never accept the humiliation of the Algerian people's honour... by opening Algerian airspace to French planes," it said.
The group called for an end to the French action against the insurgents in Mali.
The Algerian interior minister, speaking on national television, insisted Algiers would not negotiate with the "terrorists", who he said were surrounded by the army and security services.
The group appeared to want to leave the country with the hostages, which Algiers had rejected, he said. They were "around 20 men from the region," he added, denying that they had come from either Mali or Libya.
The attack took place at dawn, when armed Islamists targeted a bus carrying oil workers to the In Amenas airport, the interior ministry said. Repelled by security escorts, they instead took hostages at the gas field's residential compound.
BP confirmed in a statement that the In Amenas gas complex had been attacked at around 0500 GMT.
A Statoil official said 12 employees, including nine Norwegians, had been "implicated" in the hostage-taking, without elaborating. The company said it had just under 20 staff members at the facility.
-- 'Many lives at stake' --
A French catering company said 150 of its Algerian employees were being held at the complex.
"The information I have is that a group of around 60 terrorists from neighbouring countries attacked the base overnight," said CIS Catering's executive director Regis Arnoux.
"They took all the expatriates hostage, regardless of nationality, and tied them up. The Algerian staff are being held inside the site," he told French newspaper the Journal du Dimanche.
"We fear the worst, there are many lives at stake," he added.
Algerian news agency APS said Algerian hostages were later freed, without saying how many.
Japanese engineering firm JGC said five Japanese workers were believed to have been seized, while separate sources said a Frenchmen, an Irish citizen and a Norwegian were seized.
French news channel France 24 reported that Malaysian and Filipino nationals were also among the hostages.
The US State Department confirmed that American citizens were being held. The White House said it was "closely monitoring" the situation.
British Foreign Secretary William Hague said London was in close touch with Algiers.
"A number of people are held hostage. This does include a number of British nationals. This is therefore an extremely dangerous situation," Hague said.
One of the attackers told AFP by telephone: "We are members of Al-Qaeda and we came from northern Mali."
An Islamist spokesman told Mauritanian media the attack was "a reaction to Algeria's flagrant interference in allowing French planes into its airspace to launch raids on northern Mali."
Five hostages were being held at the gas plant, while the others were in a housing complex on the site, he added.
France launched a major offensive against the jihadists in Mali on January 11 to prevent them from advancing on the capital Bamako.
Algeria announced on Tuesday it had closed its border with Mali, following the French offensive against Al-Qaeda in its southern neighbour, but the 2,000-kilometre (1,200-mile) desert frontier is almost impossible to seal.
On Saturday, Algeria expressed its "unequivocal support" for Mali's transitional authorities. A day later Paris said Algiers had authorised overflights by France-based Rafale fighter jets for the operation there.