Alec MacLachlan was seized at Baghdad's Ministry of Finance
A body handed to UK authorities in Iraq has been identified as that of Alec MacLachlan - one of five British men seized in Baghdad in 2007.
Prime Minister Gordon Brown confirmed the 30-year-old security guard, of Llanelli, south Wales, had died.
Two of the five hostages' bodies were returned in June. The families of two others were told to expect the worst.
UK Foreign Secretary David Miliband says he believes the fifth man - IT consultant Peter Moore - is alive.
Mr Miliband earlier appealed to the men's captors.
"I renew my call, on behalf of the British government and the British people, to those holding the hostages to return them to their loved ones," he said.
BBC security correspondent Frank Gardner said Metropolitan Police forensic specialists sent to Iraq had identified the body within 24 hours of it being delivered to the British embassy.
It is believed the hostage-takers killed four of the men some time ago, our correspondent added, and efforts were now concentrating on releasing Mr Moore.
Prime Minister Gordon Brown said there was "no justification for what they have done"
"When I last met the men's families, they were still hoping reports of more deaths were untrue," our correspondent said.
Mr Moore, from Lincoln, had been working for US management consultancy Bearingpoint in Iraq when he was captured.
The other men, including Mr MacLachlan and Alan McMenemy, of Glasgow, were security contractors employed to guard him.
The group was seized at Baghdad's Ministry of Finance in May 2007 by about 40 men disguised as Iraqi policemen.
The captors were understood to belong to an obscure militia known as Islamic Shia Resistance in Iraq, which has demanded the release of up to nine of their associates held in US military custody since early 2007.
The Foreign Office insists the British government has not been directly involved in negotiations and that the Iraqi authorities have been acting as lead negotiator.
Little is known about the captives because of a media blackout during a large period of their captivity. The hostage-takers had said they did not want publicity.
The hostage crisis has been Britain's longest for nearly 20 years.
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