Forensic experts are working to establish whether a British woman was among the Islamist militants who stormed a Kenyan shopping centre leaving more than 70 dead.
Kenyan President Uhuru Kenyatta said the al Qaida-linked terrorists who overran the Westgate centre in Nairobi on Saturday have now been "defeated" - with five militants killed and 11 others in custody.
He confirmed also that intelligence reports had been received suggesting that a British woman and "two or three" American nationals had been involved in the attack. "We cannot confirm the details at present but forensic experts are working to ascertain the nationalities of the terrorists," he said in a televised address.
Announcing three days of national mourning, Mr Kenyatta said that 61 civilians and six members of the security forces had been killed in the fighting, while 62 injured remained in hospital. Towards the end of the operation, three floors of the complex collapsed and some bodies - including those of some of the terrorists - remained trapped in the rubble, he said.
"As I had promised earlier, we have ashamed and defeated our attackers. That part of our task has been completed by our multi-agency security team," he said.
"I promise that we shall have full accountability for the mindless destruction, deaths, pain, loss and suffering we have all undergone as a national family. These cowards will meet justice, as will their accomplices, wherever they are."
But while he said "the worst" of the crisis was now over, it was unclear whether Kenyan security forces had finally accounted for all the militants.
Ministers have already confirmed that there are at least six British nationals among the dead, with fears the number could rise. The confirmation that a British woman may have been among the attackers fuelled speculation that it was the terror suspect Samantha Lewthwaite, who was married to the July 7 bomber Jermaine Lindsay.
Dubbed the "White Widow", she is known to be in East Africa and is wanted by Kenyan police over alleged links to a terrorist cell that planned to bomb the country's coast. In March last year officials said she had fled to Somalia and that officers were hunting a woman who used several identities, including hers.
The Foreign Office earlier confirmed that it was aware of the claim, originally made by the Kenyan foreign minister Amina Mohamed while attending the United Nations General Assembly in New York.