Britain 'must hold its nerve on war in Afghanistan'

Speaking in Washington, Dr Fox said that the "natural impatience" to bring the troops home as soon as possible should not be allowed to cloud the important national security interests they were defending.

Premature withdrawal of Nato forces would, he said, be a "shot in the arm" to violent Islamic extremists around the world and a "betrayal" of the sacrifices made by British forces.

Afghanistan could be plunged into civil war and its nuclear-armed neighbour Pakistan dangerously destabilised, while the determination of the West to tackle international jihadists would be called into question.

His comments, in a speech to the right-wing Heritage Foundation, came just days after David Cameron said he planned to bring home British forces by the time of the next general election in 2015.

The Prime Minister's remarks alarmed some Conservative MPs who warned that he was in danger of sending mixed messages to the Taliban about Britain's willingness to stay the course in Afghanistan.

However Dr Fox, who made no reference to Mr Cameron's timetable in the text released by the Ministry of Defence, stressed that there was still important work to be done by international forces.

Although al-Qaida had been driven into the border areas of Pakistan, it continued to pose a "real and significant threat" to the West. "Were we to leave prematurely, without degrading the insurgency and increasing the capability of the Afghan National Security Forces, we could see the return of the destructive forces of trans-national terror.

Premature withdrawal "would be a shot in the arm to jihadists

everywhere, re-energising violent radical and extreme Islamism."

Downing Street rejected any suggestion that Mr Cameron and Dr Fox were at odds over the strategy on Afghanistan.

The MoD released an amended version of Dr Fox's text in which he did refer to Mr Cameron's remarks. He had added: "As David Cameron said to Parliament on Monday, the presence of large-scale (international) forces cannot be indefinite."

Following his speech, Dr Fox visited the US Walter Reed Army Medical Centre where he spoke to troops injured in the fighting in Afghanistan and Iraq.

TALIBAN ATTACKS NATO AIR BASE

Militants set off a car bomb and stormed the entrance to a major Nato air base in eastern Afghanistan in an attack which left eight insurgents dead.

The Taliban said it was behind the attack, the third ground assault against a major coalition base in the last five weeks.

The attacks have failed to overrun the bases, but showed the Taliban has not been cowed by US efforts to increase its war efforts.

Using light weapons and rocket-propelled grenades, the militants fought US and Afghan forces for 30 minutes around the airport on the outskirts of Jalalabad city.

An Afghan soldier and one international service member were wounded.