Afghanistan is not in a security crisis and disillusionment and recriminations about its situation should be avoided, a UN Security Council team said at the end of a three-day assessment tour.

There were even reasons for "cautious optimism," the delegation told reporters before wrapping up a visit which comes as attacks linked to the insurgency led by the Islamic Taliban are at record levels.

"There is undoubtedly a difficult security situation which is developing... but not a security crisis," said the head of the delegation, Italian ambassador Giulio Terzi.

"We should avoid any inclination to disillusionment and frustration or even worse to mutual recriminations between Afghanistan and its friends," he said.

"Instead, this is the time for the Afghan people and for the international community to redouble efforts and to redouble the spirit of joint partnership in overcoming these difficulties."

In his meeting with the team on Tuesday, President Hamid Karzai demanded a "timeline" for the end of largely UN-mandated international military intervention in Afghanistan.

The country is a key battleground for the US-led "war on terror" launched in 2001 with the invasion that toppled Afghanistan''s Taliban regime for harbouring Al-Qaeda after the September 11 attacks on the United States.

Karzai also said it was "unacceptable" that pockets of his country were in control of Taliban insurgents despite the presence of nearly 70,000 international troops.

Terzi said there was an expectation among all involved that the international intervention would be as short as possible, but it would also have to be sustained as long as needed and requires an increased engagement.