Secret talks between members of the Afghan government and Taliban representatives aimed at ending the war in Afghanistan have begun, a newspaper report says.

The Washington Post cited unnamed sources Wednesday who said Taliban representatives are fully authorized to speak for the Quetta Shura, an Afghan Taliban organization based in Pakistan.

"They are very, very serious about finding a way out," an unnamed source close to talks said in the report.

Mohammed Omar, the leader of the Quetta Shura, has previously said that all foreign troops must pull out of Afghanistan before talks begin.

However, the Post reports its sources say Quetta Shura representatives have entered into preliminary talks about a possible agreement that would see some Taliban members in government. The report also suggests that a timeline for the withdrawal of U.S. and NATO troops could be part of any agreement.

The sources told the Post that the talks did not include members of the Haqqani group, a separately led group that is believed to have ties to the Pakistani intelligence service.

Afghan President Hamid Karzai has not commented on the report, but the president has said previously that he would be open to peace talks with the Taliban.

NATO representatives have not responded to the newspaper report, which comes amid escalating attacks on NATO convoys travelling through Pakistan. On Wednesday, more than two dozen vehicles were destroyed after gunmen attacked the trucks at a depot in Quetta, Pakistan.

With files from The Associated Press