Mullah Abdul Salam Zaeef, once a Taliban envoy to Pakistan, recently denied plans to act as the group's “political address.”

The step was a reversal of the Taliban’s longstanding public denials that they were involved in, or even willing to consider, talks related to their insurgency, and it had the potential to revive a reconciliation effort that stalled in September, with the assassination of the head of Afghanistan’s High Peace Council.

It was unclear, however, whether the Taliban were interested in working toward a comprehensive peace settlement or mainly in ensuring that NATO ends its operations in Afghanistan as scheduled in 2014, which would remove a major obstacle to the Taliban’s return to power in all or part of the country.

In a statement, Zabiullah Mujahid, a spokesman for the Taliban, said that along with a preliminary deal to set up the office in Qatar, the group was asking that Taliban detainees held at the American prison in Guantánamo Bay, Cuba, be released. Mr. Mujahid did not say when the Qatar office would be opened, or give specifics about the prisoners the Taliban wanted freed.

“We are at the moment, besides our powerful presence inside the country, ready to establish a political office outside the country to come to an understanding with other nations,” the statement said.

American officials have said in recent months that the opening of a Taliban mission would be the single biggest step forward for peace efforts that have been plagued by false starts. The most embarrassing came in November 2010, when it emerged that an impostor had fooled Western officials into thinking he represented the Taliban and then had disappeared with hundreds of thousands of dollars used to woo him.

The official killed in September, Burhanuddin Rabbani, had been greeting a supposed Taliban negotiator when the man detonated a bomb in his turban.

The opening of an office in Qatar is meant to give Afghan and Western peace negotiators an “address” where they can openly contact legitimate Taliban intermediaries. That would open the way for confidence-building measures that Washington hopes to press forward in the coming months. Chief among them, American officials said, is the possibility of transferring a number of “high-risk” detainees — including some with ties to Al Qaeda — to Afghan custody from Guantánamo Bay. The prisoners would then presumably be freed later.

American officials said they would consider transferring only those prisoners the Afghan authorities requested. Among the names being discussed are Muhammad Fazl, the former Taliban deputy defense minister; two former provincial governors, Khairullah Khairkhwa of Herat and Noorullah Nori of Balkh; Abdul Haq Wasiq, a former top Taliban intelligence official; and one of the Taliban’s top financiers, Muhammad Nabi. Mr. Fazl is accused of having commanded forces that killed thousands of Shiite Muslims, who are a minority in Afghanistan, while the Taliban ruled the country.

The American officials said that another idea under consideration was the establishment of cease-fire zones within Afghanistan, although that prospect was more uncertain and distant. The officials asked not to be identified because of the delicacy of the talks.

Some analysts are skeptical of the prospect for meaningful peace negotiations with the Taliban. The Taliban are viewed as unlikely to cede significant ground at a time when NATO has begun to withdraw troops and intends to end combat operations here in less than three years. Another uncertainty is the role of Pakistan, which provides safe haven to Taliban leaders and has undermined past efforts at reconciliation talks that it sees as jeopardizing its interests.

But American officials have said for years that the war in Afghanistan would ultimately require a political solution. The “surge” of additional troops at the end of 2009 has largely been aimed at getting the Taliban to the negotiating table.

On Tuesday, the White House affirmed the necessity of a negotiated solution. Tommy Vietor, a spokesman for the White House’s National Security Council, said in an e-mail that such “Afghan-led peace initiatives” were central to the American strategy of “denying Al Qaeda a safe haven, reversing the Taliban’s momentum, and strengthening the capacity of Afghanistan’s security forces and government.”

Western officials stressed that a peace process was closer to the beginning than the end.

“Publicly, I don’t think we could have asked for a stronger endorsement of the peace process from the other side,” said a Western diplomat in Kabul, who asked not to be identified, in keeping with diplomatic protocol. “But this isn’t even close to having a done deal. That’s going to take years, if it even happens.”

There was no immediate comment from President Hamid Karzai of Afghanistan, who has been cool to the idea of NATO’s conducting its own talks with the Taliban, fearing a deal that would undermine his control. When word that Qatar had agreed to host a Taliban office first surfaced in December, the Karzai government rejected the notion and recalled its ambassador from the Persian Gulf state.

Afghan officials complained at the time that they had not been formally notified by the Qataris, and that they preferred that any such mission be in Saudi Arabia or Turkey. But a week ago, Mr. Karzai grudgingly agreed to Qatar as the site. Still, Mr. Karzai is likely to remain insistent that any talks be limited to reducing tensions rather than achieving a comprehensive solution to the war.

Even so, Afghanistan’s High Peace Council, appointed by Mr. Karzai, welcomed the Taliban move. Arsala Rahmani, a top negotiator on the council, called it “a gesture of good faith,” Reuters reported.

Three suicide bombings on Tuesday in the southern city of Kandahar provided a bloody reminder of the violence that continues to plague Afghanistan. Thirteen people, including a child and four police officers, were killed, Faisal Ahmad, a spokesman for the government of Kandahar Province, told The Associated Press.

Since the debacle with the impostor, the United States and its allies have focused on establishing a trustworthy channel for pursuing a peace deal with the Taliban. The push began early last year when American and German negotiators managed to make contact with a man they believed to be a legitimate representative of Mullah Muhammad Omar, the Taliban’s reclusive leader.

The Western diplomat said Tuesday that the Taliban announcement was a product of 10 months of on-again, off-again talks with the man, Tayeb Agha, a former secretary to Mullah Omar. The talks were shrouded in secrecy in large part to protect Mr. Agha and other Taliban intermediaries.

The biggest concern was that Pakistan, where most of the Taliban’s leadership is believed to reside, would obstruct any talks in which it did not play a direct role.

Afghan and American officials have long feared that Pakistan aimed to use the peace process, which it says it supports, as a way to solidify a dominant position in Afghanistan. The Qatar office is seen as a way of lessening Pakistani influence over the talks.

Sharifullah Sahak contributed reporting from Kabul, and Eric Schmitt from Washington.