Algerian forces stormed a desert gas complex to free hundreds of hostages but 30, including several Westerners, were killed in the assault along with at least 11 of their Islamist captors, an Algerian security source told Reuters, the news agency reported.

Western leaders whose compatriots were being held did little to disguise their irritation at being kept in the dark by Algeria before the raid - and over its bloody outcome. French, British and Japanese staff were among the dead, the source said.

An Irish engineer who survived said he saw four jeeps full of hostages blown up by Algerian troops whose commanders said they moved in about 30 hours after the siege began because the gunmen had demanded to be allowed to take their captives abroad.

And while a crisis has ended that posed a serious dilemma for Paris and its allies as French troops attacked the hostage-takers' al Qaeda allies in neighboring Mali, it left question marks over the ability of OPEC-member Algeria to protect vital energy resources and strained its relations with Western powers.

Two Japanese, two Britons and a French national were among at least seven foreigners killed, the source told Reuters. Eight dead hostages were Algerian. The nationalities of the rest, as well as of perhaps dozens more who escaped, were unclear. Some 600 local Algerian workers, less well guarded, survived.

The overall commander, Algerian officials said, was Mokhtar Belmokhtar, a veteran of Afghanistan in the 1980s and Algeria's bloody civil war of the 1990s. He appears not to have been present and has now risen in stature among a host of Saharan Islamists, flush with arms and fighters from chaotic Libya, whom Western powers fear could spread violence far beyond the desert.