The leader of the Afghan opposition group resisting Taliban forces in the Panjshir valley has said he welcomes proposals from religious scholars for a negotiated settlement to end the fighting.

Ahmad Massoud, head of the National Resistance Front of Afghanistan (NRFA), made the announcement on the group’s Facebook page on Sunday. Earlier, Taliban forces claimed they had fought their way into the provincial capital of Panjshir province, north of Kabul, after securing the surrounding districts.

Fahim Dashti, the spokesman for the resistance, was killed in a battle on Sunday, according to reports. Dashti was the voice of the group, an adviser to Massoud and a prominent media personality during previous governments. He was the nephew of Abdullah Abdullah, a senior official of the ousted government who has been involved in negotiations with the Taliban on the future of Afghanistan.

It comes with the US secretary of state, Antony Blinken, due to arrive in Qatar on Monday as he seeks a united front with regional allies shaken by the Taliban takeover of Afghanistan.

The Taliban took control of Afghanistan three weeks ago, taking power in Kabul on 15 August after the western-backed government collapsed and President Ashraf Ghani fled the country.

Massoud, whose forces have been the last resistance against the Islamist hardliners, said in his Facebook post that he wanted “to reach a lasting peace”.

“The NRF in principle agree to solve the current problems and put an immediate end to the fighting and continue negotiations,” Massoud said.

“To reach a lasting peace, the NRF is ready to stop fighting on condition that Taliban also stop their attacks and military movements on Panjshir and Andarab,” he said, referring to a district in the neighbouring province of Baghlan.

A large gathering of all sides with the Ulema council of religious scholars could then be held, he said.

Earlier, Afghan media outlets reported that religious scholars had called on the Taliban to accept a negotiated settlement to end the fighting in Panjshir.

There was no immediate response from the Taliban.

Massoud, who leads a force made up of remnants of regular Afghan army and special forces units as well as local militia fighters, called for a negotiated settlement with the Taliban before the fighting broke out around a week ago.

Several attempts at talks were held but they eventually broke down, with each side blaming the other for their failure.

A Taliban spokesperson, Bilal Karimi, claimed earlier on Sunday that their forces had fought their way into the provincial capital, Bazarak, capturing weapons and ammunition.

Before departing the US, Blinken said he would relay to the Qatari government America’s “deep gratitude” for acting as the gateway for 55,000 people airlifted out of Afghanistan during the chaotic Taliban takeover. It was nearly half the total evacuated by US-led forces after the Taliban’s stunningly swift victory.

Blinken plans to meet rescued Afghans as well as US diplomats, who have relocated functions from the shuttered embassy in Kabul to Doha.

On Wednesday he will head to the US airbase of Ramstein in Germany, a temporary home for thousands of Afghans moving to the United States, from which he will hold a virtual 20-nation ministerial meeting on the crisis alongside the German foreign minister Heiko Maas.

Blinken will also speak to the Qataris about efforts alongside Turkey to reopen Kabul’s ramshackle airport – a pressing priority that is necessary for flying in badly needed humanitarian aid and evacuating remaining Afghans.

The Taliban have promised that they will keep letting Afghans leave if they want to – one of the key issues that US allies expect to discuss in the talks in Germany.

The US says it will monitor the Taliban’s follow-up on commitments as it determines its future course with the Islamists, whose 1996-2001 regime toppled by US forces was notorious for an ultra-austere interpretation of Islam that included public executions and a severe curtailing of women’s rights.

US officials have said that Blinken does not plan to meet the Taliban, who have also made Doha their diplomatic base from which they negotiated the US pullout with the previous administration of Donald Trump.

Britain’s defence secretary, Ben Wallace, has suggested the United States is no longer a superpower and Armin Laschet, the leader of the German chancellor Angela Merkel’s ruling party and candidate to succeed her, described the Afghanistan mission as “the biggest debacle” in Nato’s history.

Biden, like Trump, argued that nothing more could be achieved in America’s longest war and that the Afghan government, funded by the United States for 20 years, needed to fend for itself.