David Cameron and President Hamid Karzai will today sign a pledge setting out the next stage in relations between Britain and Afghanistan.
At bilateral talks the leaders will discuss security progress as well as the future support needed from the international community following the withdrawal of troops in 2014.
That will be backed up by the signing of an "enduring strategic partnership", which renews a 2005 agreement and sets out a shared vision of a secure, stable and prosperous Afghanistan able to maintain its own security and prevent the country from being used as a safe haven for international terrorists, officials said.
It also sets out how the two countries will work together after British troops withdraw from a combat role at the end of 2014 and ensures the the UK is supporting the development of Afghanistan at the grassroots level with concrete action that directly benefits civilians, according to Downing Street.
Some of that work is already under way, including the creation of new police stations, education schemes for women and a UK-funded Afghanistan Business Innovation Fund.
It comes as France said it plans to pull out most of its troops from the country by the end of 2013 - a year earlier than the Nato deadline. President Nicolas Sarkozy made the announcement after talks with President Karzai.
The Ministry of Defence yesterday confirmed a British soldier from the 1st Battalion The Yorkshire Regiment had been killed in Afghanistan, bringing to 397 the total number of British forces personnel or MoD civilians to have died while serving in Afghanistan since the start of operations in October 2001.
The soldier, who is expected to be named today, was serving as part of Combined Force Nahr-e Saraj (North), and was taking part in an International Security Assistance Force foot patrol to disrupt insurgent activity when he received a fatal gunshot wound.
Asked about troop withdrawals during a pre-Christmas visit to soldiers serving in Afghanistan, Cameron said: "I don't want to see some massive cliff-edge in 2014 - I don't think that's practical.
"But I don't think we need to make hard and fast decisions at this stage."
He said there was "an ongoing conversation with our allies" about how and when Nato forces would be withdrawn over the next three years.
"I'm absolutely clear that the British public deserve to know there is an endpoint to our involvement in Afghanistan and that endpoint is 2014."
Saturday's meeting follows the last minute cancellation of talks in December after a series of bombings in Afghanistan in the first serious resurgence of sectarian violence in a decade.
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