LONDON // Confusion continued last night over the fate of hostages taken in a militant raid on a gas complex in southern Algeria.
Military sources were reported as saying only about 30 foreigners remained unaccounted for.
Authorities said they had ended the main assault, freed about 700 hostages and were now in a mop-up operation that included negotiations with the remaining hostage takers at the In Amenas complex.
The Algerian government news agency APS reported that nearly 100 of the 132 foreign workers kidnapped by Islamic militants had been freed.
APS also reported that only 12 hostages had died during the operation.
But western governments and Japan could not hide growing frustration at what is being regarded as a hasty Algerian military operation to end an unprecedented hostage drama that started on Wednesday.
Japan summoned Algeria's ambassador and Yoshihide Suga, Japan's chief cabinet secretary, yesterday described the operation as "regrettable".
David Cameron, Britain's prime minister, told the British parliament that he had not been informed about the operation until after it had begun.
Mr Cameron also cautioned that the hostage crisis was still continuing.
The In Amenas plant is a "large and complex site and they are still pursuing terrorists and possibly some of the hostages in other areas of the site", he said.
Reports also emerged of a proposed swap for two US hostages.
Mauritania's ANI news agency quoted sources close to Mohktar Belmokhtar, the Mali-based Algerian jihadist alleged to have masterminded the operation.
They said Belmokhtar's men were prepared to release two American hostages in exchange for the release of an Egyptian, Omar Abdul Rahman, and a Pakistani, Aafiah Siddiqui.
The pair are Islamist prisoners held in the US on terrorism charges.
The group, Signatories in Blood, also want an end to the French military intervention in Mali.
The US defence secretary, Leon Panetta, said yesterday the US was working "round the clock" to secure the safe release of its citizens and said there would be "no place to hide" for anyone who looked to attack the United States.
"Terrorists should be on notice that they will find no sanctuary, no refuge, not in Algeria, not in north Africa, not anywhere," Mr Panetta said during a visit to London.
The number of casualties so far at In Amenas was not immediately clear. Algeria has been tight-lipped about the military operation and exact numbers are unlikely to emerge until the crisis is over.
In Amenas - a wet gasfield operated through a joint venture between Algeria's Sonatrach, Britain's BP and Norway's Statoil - lies in a remote area of Algeria some 1,300 kilometres south of the capital Algiers.
But Algerian officials dismissed as "fantasy", militant claims that 34 hostages had been killed in the military assault. The government, for its part, said at least 18 of more than 30 hostage takers had been killed.
"An important number of hostages were freed and an important number of terrorists were eliminated, and we regret the few dead and wounded," Algeria's communications minister, Mohand Said Oubelaid, told national media, adding that the "terrorists are multinational", coming from several different countries with the goal of "destabilising Algeria, embroiling it in the Mali conflict and damaging its natural gas infrastructure."
APS reported that four hostages were killed in Thursday's operation, two Britons and two Filipinos. Two others, a Briton and an Algerian, died on Wednesday in the initial militant ambush on a bus ferrying foreign workers to an airport. Citing hospital officials, the news agency said six Algerians and seven foreigners were injured.
The swift and uncompromising Algerian military assault should not have come as a surprise, said Richard Cochrane, a Middle East and North Africa analyst with IHS Jane's, a group of publications focused on military and intelligence affairs based in London.
The militants had struck Algeria at a vital energy installation and embarrassed the security forces. Given Algeria's violent past, the instinct would have been to act swiftly, he said.
"Algeria's best experience of handling this kind of thing is to go in all guns blazing. That's how they've handled this kind of violence over the past 20 years," Mr Cochrane said.
But that Algeria should have been targeted in this manner also suggests that an already unstable security situation in North Africa north of the Sahel region is deteriorating, Mr Cochrane said. Libya's 2011 revolution that resulted in the overthrow of Muammar Qaddafi's regime also left a vacuum of power that militants have exploited.
Mr Cochrane suggested the Mali conflict had been fed by fighters and arms from Libya and said should the French operation there force them back out, they will be "dispersed through the region", further destabilising an area of key European energy and security interests.
North Africa "has been neglected", said Mr Cochrane. Europe needs to start focusing more on what Winston Churchill once described as its "soft underbelly".