ALGIERS: Thirty hostages and at least 11 Islamist militants were killed Thursday when Algerian forces stormed a desert gas plant in a bid to free many dozens of Western and local captives, an Algerian security source said.

Details remained scant – including for Western governments, some of which did little to disguise irritation at being kept in the dark by Algeria before the raid and its bloody outcome.

Two Japanese, two Britons and a French national were among at least seven foreigners killed, the source told Reuters. Eight of the dead hostages were Algerian. The nationalities of the rest, as well as of perhaps dozens more who escaped, were unclear.

Americans, Norwegians, Romanians and an Austrian have also been mentioned by their governments as having been captured.

Underlining the view of African and Western leaders that they face a multinational, Al-Qaeda-linked insurgency across the Sahara – a conflict that prompted France to send troops to neighboring Mali last week – the official source said only two of the 11 dead militants were Algerian, including their leader.

After an operation that appeared to go on for some eight hours, after Algeria refused the kidnappers’ demand to leave the country with their hostages, the bodies of three Egyptians, two Tunisians, two Libyans, a Malian and a Frenchman were found.

So too was that of Taher Ben Cheneb, an Algerian whom the security official described as a prominent jihadist commander in the Sahara.

The gunmen who seized the important gas facility deep in the desert before dawn Wednesday had been demanding that France halt its week-old offensive against Islamist rebels in Mali.

French President Francois Hollande said the hostage drama, which has raised fears of further militant attacks, showed that he was right to send more than 1,000 French troops to Mali to back up a West African force.

An Algerian state spokesman, who confirmed only that an unspecified number of hostages had died, said the tough response to a “diehard” attitude by the militants showed that, as during its bloody civil war against Islamists in the 1990s, Algiers would not negotiate or stand for “blackmail” from “terrorists.”

The apparent ease with which the fighters swooped in from the dunes to take control of an important energy facility has raised questions, however, over the reliability of what was thought to be strong security.

Foreign companies said they were pulling non-essential staff out of the country, which has only in recent years begun to seem stable after a decade of bloodletting.

Algiers, whose leaders have long had frosty relations with the former colonial power France and other Western nations, may also have some explaining to do over its tactics in putting an end to a hostage crisis whose scale was comparable to few in recent decades bar those involving Chechen militants in Russia. Communication Minister Mohamed Said sounded unapologetic, however. “When the terrorist group insisted on leaving the facility, taking the foreign hostages with them to neighboring states, the order was issued to special units to attack the position where the terrorists were entrenched,” he told state news agency APS, which said some 600 local workers were freed.

A local source told Reuters six foreign hostages had been killed along with eight of their captors when troops fired on a vehicle being used by the gunmen at the Tigantourine plant.

The standoff began when gunmen calling themselves the Battalion of Blood stormed the facility Wednesday morning. They said they were holding 41 foreigners.

In a rare eyewitness account of Wednesday’s raid, a local man who had escaped from the facility told Reuters the militants appeared to have inside knowledge of the layout of the complex and used the language of radical Islam.

“The terrorists told us at the very start that they would not hurt Muslims but were only interested in the Christians and infidels,” Abdelkader, 53, said by phone from his home in the nearby town of In Amenas. “‘We will kill them,’ they said.”

British Prime Minister David Cameron said people should prepare for bad news about the hostages. He earlier called his Algerian counterpart to express his concern at what he called a “very grave and serious” situation, his spokesman said.

The incident dramatically raises the stakes in the French military campaign in neighboring Mali, where hundreds of French paratroopers and marines are launching a ground offensive against Islamist rebels after airstrikes began last week.

“What is happening in Algeria justifies all the more the decision I made in the name of France to intervene in Mali in line with the U.N. charter,” Hollande said, adding that things seemed to have taken a “dramatic” turn. He said earlier that an unspecified number of French nationals were among the hostages. A French national was also among the hostage takers, a local source told Reuters. A large number of people from the former French colony live in France.

Britain said one of its citizens was killed in the initial storming Wednesday and “a number” of others were held.

The militants had said seven Americans were among their hostages. The White House said it believed Americans were among those held but U.S. officials could not confirm the number.