Two more of the British hostages held in Iraq are now thought "very likely" to be dead, the BBC has learned.
Security guards Alan McMenemy, from Glasgow, and Alec Maclachlan, from south Wales, were kidnapped in 2007 along with three other Britons.
The bodies of two of the other men were found last month with gunshot wounds.
The condition of the fifth man, Peter Moore, is not known. The Foreign Office says all efforts are being made to secure the hostages' release.
Mr Moore had been working for American management consultancy Bearingpoint in Iraq, while the other men were security contractors employed to guard him.
The group was captured at Baghdad's Ministry of Finance in May 2007 by about 40 men disguised as Iraqi policemen.
They are understood to belong to an obscure militia known as Islamic Shia Resistance in Iraq.
The group has been demanding the release of up to nine of their associates held in US military custody since early 2007.
BBC security correspondent Frank Gardner said the Foreign Office told the families of Mr McMenemy and Mr Maclachlan last week that the men had most likely died while in captivity.
And he revealed the kidnappers told the British government a month ago they had two more bodies.
"At the time the hostage-takers handed over the bodies of the two other security guards - Jason Creswell and Jason Swindlehurst - they let it be known that they had two more bodies," he said.
"They have made many claims and counter-claims and that couldn't be verified immediately. The Foreign Office is now pretty certain that it's true."
Government sources had told our correspondent that the focus was now on negotiating the release of IT consultant Mr Moore.
The last proof of life sent by his kidnappers was a video handed over in March, but it is not known when the film was made or if he is still alive today.