The UK government is to double its aid to Afghanistan for fighting the country's drugs trade, Foreign Secretary Jack Straw has announced.
Afghanistan supplies around 90% of Europe's heroin
He said Britain would give around £52m to counter narcotics programmes in the country over the next financial year.
Half of the money will be devoted to schemes to provide opium poppy farmers with alternative sources of income.
Mr Straw made the commitment after talks with the Afghan president Hamid Karzai in Kabul on Wednesday.
Some 90% of the heroin consumed in Britain and Europe comes from Afghanistan's poppy fields.
Since allied forces ousted extremist Taleban rulers in December 2001, opium production has increased twenty fold.
Tackling the drugs trade is a key element of UK policy in Afghanistan.
Training an elite police unit to go after heroin labs and traffickers has been one course of action.
Speaking at a joint conference with President Karzai, Mr Straw said: "This is a joint problem but also a joint responsibility."
The foreign secretary also announced the appointment of Lieutenant General John McColl as the UK prime minister's special envoy for Afghanistan.
The talks, part of Mr Straw's tour of South Asian countries, are also due to cover security and the needs of refugees.
The foreign secretary has been a regular visitor to Afghanistan because of the UK's role in efforts to help the country rebuild.
Britain has several hundred troops with the Nato-led peacekeeping force, as well as smaller numbers with the US-led coalition.
Mr Straw will be in Kabul for one day. He has already visited Pakistan and India during the past two days.