The United States and its NATO allies are losing in Afghanistan because of a lack of coordination and broad commitment, one of Britain's top diplomats and defence experts said on Tuesday.

Paddy Ashdown, the former British representative for Bosnia and once tipped to be the U.N. special representative in Afghanistan, said the U.S.- and NATO-led coalition faced defeat unless operational changes were made.

"We're losing," Ashdown told an audience of defence experts at the launch of a new British security strategy in London.

"We're on our way to losing and our young men are dying out there because politicians won't get their act together," he said, referring to political leaders across NATO.

The British seem to think Helmand, a restive province in southern Afghanistan, is the biggest problem, he said, while the Dutch focus on Oruzgan, another province, the Canadians on Kandahar, the Germans on another portion in the north of the country and the Americans on a different set of priorities.

"Everyone is pulling in different directions and that's the worst threat in Afghanistan there is," said Ashdown, 68, a former member of Britain's Royal Marines.

His comments come as President Barack Obama is ramping up the U.S. presence in Afghanistan, sending up to 20,000 more troops, including around 10,000 Marines to support nearly 8,000 British troops deployed in Helmand.

Obama has also replaced the U.S. general leading the war, appointing General Stanley McChrystal, a former special forces commander, to oversee the vast operation.

There are around 90,000 foreign troops in Afghanistan, 57,000 of them American and the remainder from more than 40 nations, from Britain to Bulgaria.

Ashdown's comments were made at the launch of a new security and defence strategy put together by a team of defence experts assembled by the Institute for Public Policy Research, a leading British think-tank.

The 143-page report compiled by the panel, which included Ashdown, George Robertson, the former secretary-general of NATO, Jeremy Greenstock, Britain's former ambassador to the United Nations, and the former head of Britain's defence staff, had stern proposals for resetting course in Afghanistan.

"If we do not address the almost total lack of effective coordination of the international effort in Afghanistan, we will continue to make only slow progress and will pay the price in lives of soldiers and Afghan civilians," the report said.

"The international community needs a single plan for Afghanistan, developed in partnership with the Afghan authorities, with tightly defined priorities and a determination by all members of the international community to operate it with real unity of purpose and voice."

Specifically of Britain, the report said the government should direct more resources at the situation in Pakistan and work much harder to integrate military operations with the work of the Department for International Development, an aid arm.