(CNN) — The Taliban have met with U.S. officials to discuss possible peace talks, but do not want to negotiate with Afghan President By Nick Paton Walsh and Hamid Karsai’s government, a Taliban spokesman said Tuesday.

The spokesman’s comments, rejecting a key American condition, could potentially derail American efforts for Afghans to reach a negotiated end to the decade-long war.

In an e-mail response to questions from CNN, Taliban spokesman Zabiullah Mujahid denied previous reports that the Taliban had been invited to meet with the Karzai government in Saudi Arabia, saying that talks with what he called a “puppet” government would be pointless.

“We have never been asked to attend talks with Karzai administration officials in Saudi Arabia, but even if we are asked to attend, we won’t because (the) Karzai government is a puppet and unauthorized, and meeting with them will not be beneficial in solving the issue,” Mujahid wrote in a message from an e-mail account regularly used by the Taliban to issue statements.

The spokesman, in answers that he said had taken some time to consider, said the Taliban wants direct discussions with the Americans.

“The issue is … who is powerful and has got the power to make a decision, and who hasn’t, and everyone around the world knows that the one who has got the authority in opposition to the Mujahideen (the Taliban) is America,” he wrote.

The e-mail also contained the Taliban’s first open recognition that they have met with U.S. officials in Qatar — talks that senior American officials also confirmed.

The talks with the Taliban are aimed at establishing what the senior U.S. officials called “confidence-building measures” to lay the groundwork for negotiations between the Afghan government and the Taliban, with the United States possibly serving in a mediation role.

U.S. officials have been trying to jump-start peace talks between the Taliban and Afghan officials through discussions over the past year.

The nascent process has been marred by dissatisfaction from Afghan government officials that they were not included at the start. Karzai’s advisers have complained that U.S. officials were going behind Kabul’s back in talking to the Taliban.

After initially opposing U.S.-Taliban talks, Karzai has since given his blessing, paving the way for a meeting last month between U.S. envoy Marc Grossman and Taliban representatives in Doha, Qatar, senior U.S. officials said.

The Taliban’s demand to talk with U.S. officials and not the Karzai administration could throw a wrench in the U.S. State Department’s demand that all talks be Afghan-led and Afghan-owned.

Another meeting between U.S. officials and Taliban representatives could happen this month, the senior U.S. officials said.

The officials said the likelihood of reaching a deal between the Afghan government and the Taliban is slim. The talks could sow discord in the Taliban ranks, between those who want to negotiate and those who don’t, the senior U.S. officials said.

On Tuesday, Mujahid said that the Taliban sought confidence-building measures from the Americans for talks to proceed.

“The trust-building phase is totally up to Americans,” the spokesman wrote, “and they have to take measures and our conditions are as follows: Exchange of Guantanamo prisoners, the establishment of political office (in Qatar), removing the sanction lists of the UN (against Taliban figures).”

American demands for the Taliban include requiring them to renounce terrorism and to distance themselves from al Qaeda, senior U.S. officials said. Taliban representatives seemed organized, professional and willing to meet those demands during the Qatar talks, according to the senior U.S. officials.

— CNN’s Elise Labott contributed to this report.