Lawmakers criticised US policies in Afghanistan and Pakistan and warned the "considerable cultural insensitivity" of some coalition troops had caused serious damage to Afghans' perceptions that will be "difficult to undo".

"We conclude that the international effort in Afghanistan since 2001 has delivered much less than it promised and that its impact has been significantly diluted by the absence of a unified vision and strategy grounded in the realities of Afghanistan's history, culture and politics," the report said.

"Although Afghanistan's current situation is not solely the legacy of the West's failures since 2001, avoidable mistakes, including knee-jerk responses, policy fragmentation and overlap, now make the task of stabilising the country considerably more difficult than might otherwise have been the case."

As for Britain's roughly 9,000 troops in Afghanistan -- who in July suffered their worst month since the 2001 invasion with 22 deaths -- the members of parliament (MPs) said their role has seen "significant mission creep".

They were initially sent to counter international terrorism and are now working on areas like fighting the drugs trade and counter-insurgency, it said, adding the military had not been given "clear direction".

"We conclude that the UK's mission in Afghanistan has taken on a significantly different and considerably expanded character since the first British troops were deployed there in 2001," the report said.

"The UK deployment to Helmand (province) was undermined by unrealistic planning at senior levels, poor coordination between Whitehall (government) departments and crucially, a failure to provide the military with clear direction."

Britain's role as lead international partner on counter-narcotics was "a poisoned chalice", the report said, adding there was "little evidence" to suggest that cuts in poppy cultivation were down to deliberate strategy.

It called for British troops to focus on security alone.

The "Global Security: Afghanistan and Pakistan" report also looked at problems caused by the use of air power, particularly by the United States.

Drone attacks by US forces in Pakistan have "damaged the US's reputation" while some of the blame for problems in the international mission in Afghanistan must be put on the Bush administration's early focus on military goals, it said.

The report also warned that the reputation of NATO -- in command of international troops in Afghanistan since 2003 -- could be "seriously damaged" without fairer burden-sharing between member states to ease the strain.

Britain has long called for other NATO countries to contribute more to the military effort.

The conditions of prisoners and detainees being held by the Afghan authorities were "a matter of considerable concern", it added, while also saying there had been "no tangible progress" on tackling corruption.

Responding to the report, the Foreign Office said it would study its conclusions and submit an official response in the coming months.