KABUL: The top commander in Afghanistan said Tuesday that he was not surprised by reports that an impostor was involved in peace talks with the Afghan government because there were long-held doubts about one of the alleged Taliban representatives.

In a setback to efforts to negotiate an end to the war, an Afghan close to the negotiations said the man, Mullah Akhtar Mohammad Mansour, who claimed to be one of highest ranking members of the Taliban council leading the insurgency, was a fraud.

Speaking to reporters in Berlin, Gen. David Petraeus said there had been skepticism all along regarding the identity of one man claiming to be a Taliban leader.

''It may well be that that skepticism was well-founded,'' Petraeus said.

President Hamid Karzai moved quickly to dampen the fallout from his alleged meeting with Mansour by denying the encounter ever took place.

He dismissed the reports, which first appeared in The New York Times and The Washington Post, as propaganda.

''I did not see Mullah Akhtar Mohammad Mansour and Mullah Mansour did not come to Afghanistan. Don't accept this news from the foreign press regarding meetings with the elders of the Taliban because most of them are propaganda,'' Karzai said.

An Afghan familiar with the reconciliation efforts, confirmed that a delegate claiming to be Mansour ''was a fraud.'' He spoke on condition of anonymity so as not to jeopardize his contacts with both sides.

Mansour, a former civil aviation minister during Taliban rule, is a senior member of the Taliban's ruling council in the Pakistani city of Quetta. That council, or shura, is run by Taliban leader Mullah Mohammad Omar.

According to the reports, the impostor met with Afghan and Nato officials three times including once with Karzai before they discovered he was not Mansour. He was allegedly paid to attend.

Mansour was well-known and it is unclear why officials would have had such a difficult time identifying him. There are a number of former Taliban in parliament and in the 70-member High Peace Council recently formed by Karzai to find a political solution to the insurgency. It was reported that the man was believed to be a shopkeeper in Quetta.

If confirmed, the claims that he was not really involved would be a blow to the Afghan government's push to find a political resolution to the nine-year-old war. It raised questions about the credibility of some Nato officials who have said they facilitated contacts between Taliban figures and Afghan officials.

The president also took the opportunity Tuesday to complain about some of Nato's military operations aimed at crushing the insurgency.

Karzai expressed his concerns about night raids, which have caused friction between him and international forces, at a weekend summit with Nato leaders in Lisbon, Portugal.

Nato says the night raids have taken a significant toll on the leadership of insurgent networks.

''The position and stance of the Afghan government was very clear and is very clear,'' Karzai said. ''Those night raids which cause civilian houses to be destroyed, cause civilian causalities or they are entering people's houses without coordinating with the Afghan forces ... we are against them.''

The coalition hopes night raids will weaken the Taliban by pressuring the midlevel commanders to abandon the battlefield and force top insurgent leaders to the negotiating table. Nato says it conducts the operations jointly with Afghan soldiers and that shots are fired in less than 20 per cent of the operations.

Karzai did praise the long-term partnership agreement that Nato has made with Afghanistan, and reassured the Afghan people that Nato's support would not cease after 2014 when Nato's combat role is set to end.

Meanwhile, there were developments in the ongoing dispute over the rule of private security companies in Afghanistan. Gen. Abdul Manan Farahi, the Interior Ministry official in charge of overseeing security firms told the AP, they could continue protecting aid and economic development projects in the country until their current contracts expire.

The decision comes despite an earlier order that all security companies disband by mid-December.

It also clears up uncertainty that had been hanging over large companies involved with ongoing aid and development projects for the US and other foreign governments since a presidential decree to disband them was issued in August. – AP