KABUL (Reuters) - Pressure is building on the Taliban to respond to President Ashraf Ghani’s offer for peace talks, in the face of growing demands for an end to the 17-year-long war in Afghanistan, a senior U.S. official said.

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“Increasingly, I think it’s becoming unacceptable for the Taliban not to negotiate,” Principal Deputy Assistant Secretary for South and Central Asia Alice Wells told reporters during a visit to Kabul.

“Right now it’s the Taliban leaders, and frankly it’s Taliban leaders who aren’t residing in Afghanistan, who are the obstacle to a negotiated political settlement,” said Wells, one of the State Department’s top officials dealing with Afghanistan.

Her remarks were made on Saturday but embargoed for release on Sunday.

The Taliban, fighting to restore their version of strict Islamic law after being toppled by a U.S.-led campaign in 2001, have so far rebuffed Ghani’s call for talks following a three-day ceasefire over the Eid holiday last month.

Instead, they have accused civil activists and local groups urging a truce of playing into the hands of the United States, which they say must pull its troops out of Afghanistan for talks to begin.

However, Wells said there was widespread support for peace, underlined by scenes of unarmed fighters mingling with government troops and civilians on the streets of Afghan cities during Eid.

“The support that we saw, not just from the Afghan people but from the Taliban commanders and foot soldiers was extraordinary,” she said.

On Saturday, President Ghani ordered government troops to resume normal operations following a voluntary extension of the Eid ceasefire and repeated his offer to the Taliban to open peace talks.

Wells said a U.S. offer to join peace talks and discuss the future of international troops in Afghanistan had removed any justification for the Taliban’s refusal to negotiate with the Afghan government, which they consider a puppet regime.

“It really takes away all of the objections the Taliban have about why they are not prepared to engage with the Afghan government,” she said.

Wells, who is due to meet officials in Islamabad on Monday, said neighboring countries had a vital role to play in pushing the process ahead but Pakistan was not doing enough. “We have not yet seen that sustained and decisive action on the part of Islamabad and that’s what we’re looking for,” she said.

Afghanistan accuses Pakistan of fostering the Taliban by providing support as well as a safe haven for its leaders, a charge Islamabad denies, instead pointing to the heavy toll its own people have suffered from militant attacks.