Algerian Gendarmes escort a freed Norwegian hostage Oddvar Birkedal (C) at a police station in In Amenas January 19, 2013. The Algerian army on Saturday carried out a final assault on al Qaeda-linked gunmen holed up in a desert gas plant, killing 11 of the Islamists after they took the lives of seven more foreign hostages, a local source and the state news agency said.

ALGIERS/IN AMENAS: The international hostage crisis has ended in a bloodbath.

The Algerian army carried out a dramatic final assault to end a siege by Islamic militants at a desert gas plant yesterday, killing 11 al-Qaeda-linked gunmen after they took the lives of seven more foreign hostages.

Earlier yesterday, Algerian special forces found 15 unidentified burnt bodies at the plant which militants tried to set alight on Friday.

The state oil and gas company, Sonatrach, said the militants who attacked the plant on Wednesday and took a large number of hostages, had booby-trapped the complex with explosives which the army was removing.

“It is over now, the assault is over, and the military are inside the plant clearing it of mines,” a source said.

The exact death toll among the gunmen and the foreign and Algerian workers at the plant near the town of In Amenas remains unclear, although reports point to several dozen people being killed.

The attack on the gas plant tested Algeria’s relations with the outside world, exposed the vulnerability of multi-national oil operations in the Sahara and pushed Islamic radicalism in Africa to centre stage.

As the army closed in, 16 foreign hostages were freed, a source said. They included two Americans, two Germans and one Portuguese. Britain said fewer than 10 of its nationals at the plant were unaccounted for.

BP’s chief executive Bob Dudley said four of its 18 workers at the site were missing. The rest were safe.

The crisis at the gas plant marked a serious escalation of unrest in northwestern Africa, where French forces have been in Mali since last week fighting an Islamist takeover in the north.

The captors said their attack on the Algerian gas plant was a response to the French offensive in Mali. However, some US and European officials say the elaborate raid probably required too much planning to have been organised from scratch so quickly.

Scores of Westerners and hundreds of Algerian workers were inside the heavily fortified gas compound when it was seized before dawn on Wednesday by Islamists who said they wanted a halt to the French intervention in Mali.

Hundreds escaped on Thursday in a rescue operation by the army, but many hostages were killed.

Before the final assault, the number of hostages killed was variously reported to be between 12 and 30, with many foreigners still unaccounted for.

An Algerian security source said eight Algerians and at least seven foreigners were among the victims, including two Japanese, two Britons and a French national. One British citizen was killed when the gunmen seized the hostages on Wednesday.

Leading the attack on the plant was a fighter from Niger called Abdul Rahman al-Nigeri, according to Mauritanian news agencies. His boss, Mokhtar Belmokhtar, a veteran of fighting in Afghanistan and Algeria’s civil war, appears not to have joined the raid.

Britain and other countries expressed irritation that the army assault was ordered without consultation.

But French president Francois Hollande said the Algerian military’s response seemed to have been the best option in the circumstances.

“When you have people taken hostage in such large number by terrorists with such cold determination and ready to kill those hostages – as they did – Algeria has an approach which to me, as I see it, is the most appropriate because there could be no negotiation.”

The most powerful Islamist groups operating in the Sahara were severely weakened by Algeria’s military in the civil war in the 1990s. But in the past two years the regional wing of al-Qaeda gained fighters and arms as a result of the civil war in Libya, when arsenals were looted.

France says the hostage incident proves its decision to fight Islamists in Mali was necessary. Al-Qaeda-linked fighters took control of northern Mali last year. – Lamine Chikhi and Abdelaziz Boumzar for Reuters