The Foreign Secretary has called for the "immediate and unconditional" release of five British hostages held in Iraq for nearly two years.
The men - who were civilian contractors - were seized by dozens of gunmen in Baghdad on May 29 2007.
In a statement released ahead of the abduction's two-year anniversary, David Miliband spoke of the "anguish" suffered by their families, saying: "We call on those holding all hostages to release them immediately and unconditionally and return them safely to their families where they belong."
The kidnap victims - who have not been officially named - are IT consultant Peter Moore and four security guards.
They were abducted by about 40 gunmen wearing police uniforms at the Iraqi Finance Ministry.
Videos of the captives have since been released following their capture, the last of which in March showed Mr Moore saying they were being treated well and urging the British government to secure their release.
In a previous video, broadcast by Dubai-based Al-Arabiya television in December 2007, the kidnappers threatened to kill the men unless British troops were pulled out of Iraq within 10 days.
Mr Miliband said: "I don't think that any of us can imagine their ordeal, nor the anguish that their families and friends have had to suffer during this dreadful time.
"Our thoughts are with them all as they continue to endure the pain of being separated from their loved ones."
He added that he was "totally committed" to securing the men's release.
"There is a dedicated team from across government, including people on the ground in Baghdad, working tirelessly with the Iraqi authorities and Coalition partners to help bring this about."
Mr Miliband also said Iraq - where British combat operations formally ended earlier this month - was "a different place to that of two years ago".
"There are signs of progress and reconciliation as the Iraqi people show their commitment to a democratic and peaceful future.
"Hostage-taking has no part in that future. We call on those holding all hostages to release them immediately and unconditionally and return them safely to their families where they belong."
Mr Moore is thought to have worked for BearingPoint, an American management consultancy, while the other four hostages were working for Canadian firm GardaWorld as security guards.
At the time of their kidnapping, Iraqi officials blamed the Mahdi Army, the militia controlled by the radical Shiite cleric Muqtada al-Sadr.
It was thought to be a retaliatory attack for the killing by British forces of the militia's commander in Basra, southern Iraq, a week earlier.
But al-Sadr's followers have denied responsibility and suspicion has since fallen on splinter groups which the US believes are controlled by Iran.
In February last year a video of Mr Moore was released, in which he said: "My name is Peter Moore, I have been held here for nearly eight months now."
He asked Gordon Brown to free nine Iraqis in exchange for their release.