WASHINGTON — The United States said Wednesday it has taken no decision to release prisoners held at Guantanamo Bay in order to boost reconciliation talks with the Taliban.

But State Department spokeswoman Victoria Nuland said Washington is "prepared to support" a proposed overseas Taliban office that backs an Afghan-led reconciliation process provided it meets US and Afghan standards.

She said the United States and Afghanistan seek true reconciliation based on the Taliban's renouncing violence, breaking with Al-Qaeda and embracing the Afghan constitution, which enshrines human rights.

"With regard to Guantanamo... no decisions have been made with regard to any releases," Nuland said.

The hardline Taliban announced on Tuesday that they had come to an "initial agreement with relevant sides including Qatar" to set up their first representative office outside Afghanistan.

The move is seen as a precursor to talks to end the bloody war between the Taliban and the US-backed government of President Hamid Karzai.

It is the first time the insurgent group has publicly raised the prospect of a negotiated peace after more than 10 years of fighting, always previously insisting they would not talk until all foreign troops had left Afghan soil.

One of their demands would be for a prisoner exchange to include the release of Taliban inmates from the US-run detention facility at Guantanamo Bay, Cuba, the Taliban said.

Asked if Afghanistan had formally requested the release of such prisoners, Nuland replied: "We're not today, we're not in the future going to get into the details of these Afghan-led discussions. That's not productive to the process."

Earlier Wednesday, the government of Afghanistan gave its blessing to talks between the Taliban and the United States, and also to the opening of an office for the Islamists in Qatar.

The United States has admitted to holding exploratory talks with the Taliban and the Taliban-related Haqqani network.

Vali Nasr, who was an Obama administration adviser on the Afghan peace process until last year, said a Taliban office in Qatar would be "significant" because it offers the prospect of moving from secret to open and formal talks.

But Nasr, a professor of international politics at Tufts University, told AFP such open negotiations would be "politically risky" for both the United States and the Taliban if they produce nothing.

He said he believed the proposal for a Qatar office "could not have been arrived at unless there was some kind of a back-and-forth discussion" about the US transferring Taliban prisoners from Guantanamo to some other facility.

Nasr, who did not think such prisoners would actually be released from custody, said the transfers would give the Taliban "enough political capital" to enter talks with the United States and the Afghan government.