FEARS remain for the safety of British workers caught up in the terrorist attack on an Algerian gasfield after the Government said the incident was "ongoing".
At least one British national has been killed in the desert siege and Prime Minister David Cameron warned that the nation "should be prepared for bad news".
The Algerian authorities announced that there had been "some deaths and injuries" after launching a military bid, without informing the UK, to free foreign workers from Islamist militants.
Algeria's state news agency APS claimed the crisis ended last night but the Foreign Office said today that the incident is not over.
Mr Cameron will make a statement to the Commons to update MPs on the latest developments at the gasfield at In Amenas after chairing a meeting of the Cobra emergencies committee.
Foreign Secretary William Hague, who is cutting short a visit to Australia, told Sky News: "This remains a fluid and evolving situation and many details are still unclear, but the responsibility for the tragic events of the last two days squarely rests with terrorists who chose to attack innocent workers, murdering some and holding others hostage.
"Our priority remains at the moment to identify exactly what has happened to each British national caught up in this incident and, indeed, to help other countries determine what has happened to their nationals."
The Algerian rescue effort was launched yesterday without consultation with the UK, to the dismay of Number 10.
Mr Cameron was informed that it was under way when he telephoned his Algerian counterpart, Abdelmalek Sellal, yesterday morning despite having earlier asked to be kept fully updated.
Offers of British help had been declined.
Algerian communications minister Mohamed Said Belaid said the military operation succeeded in "neutralising a large number of terrorists and freeing a large number of hostages".
"But unfortunately, we are sorry to say, there were some deaths and injuries," he said.
A Belfast man caught up in the siege escaped the complex yesterday and made contact with his family to say he was safe and well.
Mr Cameron cancelled his long-awaited Europe speech which he had been due to deliver in the Netherlands today after a second call to Mr Sellal.
Downing Street said Mr Cameron had "emphasised the continuing need for the Algeria security forces to do everything they could to safeguard hostages".
Speaking afterwards, he said: "We should be prepared for the possibility of further bad news, very difficult news, in this extremely difficult situation."
Officials would continue "working around the clock to do everything we can to keep in contact with the families, to build the fullest possible picture of the information and the intelligence".
"I will do everything I can to update people about what is a difficult and dangerous and potentially very bad situation," he added.
The militant group believed to have carried out the raid on the gas plant said it was in retaliation for French military intervention against al Qaida-backed rebels in neighbouring Mali.
The drama began on Wednesday morning when heavily-armed militants launched a dawn raid, killing two people and injuring six others.
They claimed to have seized 41 foreign workers including Britons, Americans, Norwegians and Japanese.
A spokesman for the militants claimed that 35 hostages and 15 rebels were killed when Algerian helicopters strafed the site in yesterday's operation.
The militants - reportedly led by the veteran jihadist Mokhtar Belmokhtar - threatened previously to "eliminate" the hostages if they were attacked.