CAIRO -- An al-Qaida operative known as the "Uncatchable" has claimed responsibility for the attack on an Algerian natural gas complex in the desert that led to the deaths of at least 23 foreign hostages and raised new fears of Islamic extremism in North Africa.
The comments by Mokhtar Belmokhtar, a veteran Islamic militant and arms trafficker, came as the U.S., Britain and other countries sought to learn the fate of their citizens after Algerian authorities announced Sunday that the hostage death toll was expected to rise.
"I am afraid unfortunately to say that the death toll will go up," Algerian Communications Minister Mohamed Said Belaid told the state news agency. He added that the aim of the extremists, 32 of whom were killed during the siege, was to blow up the refinery and execute all the hostages.
Bomb units defusing booby-trap explosives at the Sahara site discovered 25 burned and disfigured bodies, according to a private Algerian TV station. That would push the overall number of deaths to at least 80. Authorities also said the Algerian army captured five militants hiding at the sprawling facility.
International security and intelligence officials remained perplexed over how a band of nearly 50 Islamic militants last week overran the gas complex on the Algerian-Libyan border. Mr. Belmokhtar's claims -- reported from a video received by the Sahara Media website -- suggest al-Qaida in the Islamic Maghreb had sanctioned the attack to avenge French airstrikes last week on rebels in neighboring Mali.
"We in al-Qaida announce this blessed operation," Mr. Belmokhtar is quoted as saying in the video, which the website did not immediately air. "We are ready to negotiate with the West and the Algerian government provided they stop their bombing of Mali's Muslims."
A notorious kidnapper who fought in the 1990s Algerian civil war, Mr. Belmokhtar claimed the refinery raid was carried out by "around 40 jihadists, most of them from Muslim countries and some even from the West."
Officials from the U.S. and other countries have indicated that the attack appeared to have been planned ahead of this month's French military intervention to stop rebels from advancing in Mali. It was not clear if the militants, who appeared to have contacts inside the plant, used the Mali conflict as the impetus for acting on an existing plan.
As many as seven U.S. hostages were still missing Sunday, along with about 14 Japanese. Other plant workers unaccounted for included Norwegians, Malaysians, Britons and French. Three Britons and one American have been confirmed dead.
Nearly 700 Algerians and 107 foreigners had been freed or escaped from the gas field in eastern Algeria during the bloody four-day ordeal that ended Saturday. Discrepancies remained over the nationalities of the dead hostages and the exact number of those who perished.
"This is a stark reminder once again of the threat we face from terrorism the world over," British Prime Minister David Cameron said Sunday. "We have had successes in recent years in reducing the threat from some parts of the world, but the threat has grown particularly in northern Africa."
French Defense Minister Jean-Yves Le Drian also foreshadowed the longer term implications faced by the West in routing extremist networks scattered across lawless deserts and mountains.
"What strikes me the most is that we're saying 'hostage-taking,' but when there are so many people concerned, I think this is an act of war," he told French TV.
Claims by militants and accounts from freed hostages suggest that more than 20 captives may have been killed Thursday when gunfire from a military helicopter struck as many as five vehicles moving inside the refinery grounds. The murky details of that incident have raised questions among international officials over the way Algerian officials planned and carried out their response.
Mr. Cameron, who had earlier appeared irritated that the Algerians did not inform foreign capitals before troops first stormed the refinery Thursday, tempered his criticism Sunday.
"People will ask questions about the Algerian response to these events," he said. "But I would just say that the responsibility for these deaths lies squarely with the terrorists who launched this vicious and cowardly attack. And I'd also say that when you're dealing with a terrorist incident on this scale, with up to 30 terrorists, it is extremely difficult to respond and to get this right in every respect."
The natural gas complex in a town called In Amenas is operated by BP, Statoil and Sonatrach, the Algerian national oil company.world