WASHINGTON (Reuters/AFP) - Representatives of the Taliban and President Hamid Karzais government have started secret talks to negotiate an end to the war in Afghanistan, The Washington Post reported on Tuesday, citing Afghan and Arab sources. The sources, who were not named by the Post, were quoted as saying they believe the Taliban representatives are authorised to speak for the Quetta Shura, the Afghan Taliban organisation based in Pakistan, and its leader, Mullah Muhammad Omar. The sources quoted by the Post stressed that the current discussions are in the preliminary stages. The newspaper said the talks followed inconclusive meetings hosted by Saudi Arabia that wrapped up more than a year ago. Karzais spokesman Waheed Omer, speaking in Kabul, declined to confirm or deny the report of new meetings. There were contacts in the past and may now be direct or indirect ones. There have been regular contacts over the past two years, he said, when asked about the Washington Post story. There havent been any substantive talks, there have been contacts only. They are very, very serious about finding a way out, one source close to the talks said of the Taliban, according to the Post. The newspaper noted that Omars representatives have insisted publicly that negotiations were impossible until foreign troops withdraw from Afghanistan. But the Post said the Quetta Shura has begun to discuss a broad agreement that would include participation of some Taliban figures in Afghanistans government and the withdrawal of US and NATO troops on an agreed timeline. The Post quoted several sources as saying that the talks with the Quetta Shura did not involve the Haqqani network, the target of US drone attacks in northwestern Pakistan. Afghan, Arab and European sources cited by the Post said they saw a change of heart by the US towards backing such negotiations, saying the Obama Administration only recently appeared open to talks rather than resisting them. The White House, meanwhile, backed the idea of Afghan government reconciliation talks with the Taliban, but said the United States was not a party to reported contacts between Kabul and militia leaders. White House spokesman Robert Gibbs said the Obama Administration had long supported an Afghan-led reconciliation effort, though did not specifically confirm the contents of the Post report. We and the Afghans have said that ... requires a renunciation of Al-Qaeda, following Afghan law and a renunciation of violence, he said, adding that such talks had to be conducted by Afghans. Earlier on Tuesday, Pentagon Press Secretary Geoff Morrell said a broad Taliban shift towards reconciliation with the Afghan government was unlikely for now. I think it is too soon to suggest that there is ... a wider movement afoot, that the tide is turning in terms of re-integration and reconciliation, Morrell told reporters at a briefing at the Pentagon. We need to take the fight more aggressively and for a greater duration to the Taliban and other extremists in Afghanistan for them to feel the kind of pressure necessary for there ... to spark a movement of reintegration and reconciliation, Morrell said. The operational tempo that were now undertaking is extraordinarily fast, he said. We have more troops than weve ever had before conducting more operations than ever before and the Taliban is clearly feeling it. Meanwhile, Taliban leader Mullah Omar has, for the first time, backed secret high-level talks with the Afghan government to negotiate an end to the nine-year war, the Washington Post said Wednesday. They are very, very serious about finding a way out, a source close to the talks told the Post, referring to the Taliban. They know that more radical elements are being promoted within their rank and file outside their control, the source said. All these things are making them absolutely sure that, regardless of (their success in) the war, they are not in a winning position.