KABUL, Afghanistan — A man leading the Taliban side of peace talks with the Afghan government was an impersonator, an Afghan close to the negotiations said today, in a setback to efforts to negotiate an end to the war.

President Ahmed Karzai has moved quickly to dampen the fallout from his alleged meeting with a man named Mullah Akhtar Mohammad Mansour — supposedly one of highest ranking members of the Taliban council leading the insurgency — by denying the encounter even took place.

He dismissed the reports 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.