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Three Britons are confirmed to have been killed and three more are believed to be dead after the Algeria hostage crisis, the prime minister has said.
One further UK resident is also thought to be dead, David Cameron said.
An unknown number of Britons have survived. Some returned to the UK overnight, the Foreign Office said.
A raid by Algerian troops ended a four-day siege at the In Amenas gas facility on Saturday. At least 23 hostages died and Algeria says 32 militants died.
The Foreign Office said the figures announced by the prime minister included a Briton killed on Wednesday in the initial raid by militants.
'Cowardly attack'
Speaking at Chequers, Mr Cameron said the priority now was to get the surviving hostages home from Algeria.
He said: "I know the whole country will want to join me in sending our sympathies and condolences to the families who have undergone an absolutely dreadful ordeal and who now face life without these very precious loved ones."
The prime minister said questions would be asked about the Algerian response to the crisis, but he added: "The responsibility for these deaths lies squarely with the terrorists who launched this vicious and cowardly attack."
The crisis began on Wednesday when militants attacked two buses carrying foreign workers the remote site in south-eastern Algeria.
The militants then took Algerians and foreign workers hostage at the complex, which was quickly surrounded by the Algerian army.
A statement from the kidnappers said the assault on the gas plant was launched in retaliation for French intervention against Islamist groups in neighbouring Mali.
However, France only decided last week to intervene militarily in Mali. Analysts say the assault on the gas facility was well-planned and would have required advance research, as well as possibly inside help.
The Algerian armed forces attacked on Thursday as militants tried to move some of their captives from the facility.
- BBC
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