The international community must "up its game" on political progress in Afghanistan or risk wasting a decade of sacrifice by British soldiers, Labour leader Ed Miliband has warned.
Mr Miliband expressed fears that the country would slip back into being a failed state when combat troops are withdrawn in 2014, during a visit to the capital Kabul for talks with president Hamid Karzai.
He flew in after visiting troops serving in southern Helmand, where he expressed surprise at the level of progress being made in training the Afghan security forces ahead of the international pullout.
Despite giving his backing to the planned withdrawal date - reaffirmed at last weekend's Nato summit in Chicago - and to Prime Minister David Cameron's approach, he said there was "a long way to go".
In an address to troops at the end of a tour of British bases, Mr Miliband told a gathering of troops that political failure must not be allowed to undermine their "extraordinary" efforts.
A total of 414 members of UK forces have died since operations in Afghanistan began in October 2001.
Speaking at the British Embassy ahead of talks with Mr Karzai - as well as senior ministers and opposition leader Abdullah Abdullah - he said: "It is incredibly eye-opening coming out and actually seeing what they are doing, throwing themselves in harm's way, every day going out on patrol.
"Seeing it up close, with people who are young enough to be my son or daughter doing that, is incredibly humbling.
"I think the best way we can honour the sacrifices our troops have been making is to make sure that they have the best support when they come back home.
"But also, the international community needs to up its game in getting a lasting political settlement here in Afghanistan because I think that is necessary in order to prevent Afghanistan slipping back into being a failed state and there is a lot more work to do to make that happen."