Afghanistan's new Taliban rulers were preparing their government on Thursday, more than two weeks after the militia's capture of Kabul brought a chaotic end to 20 years of war, while the economy teetered near collapse.

Taliban official Ahmadullah Muttaqi said on social media a ceremony was being prepared at the presidential palace in Kabul and Taliban spokesperson Zabihullah Mujahid said a new government was a matter of a few days away.

The legitimacy of the government in the eyes of international donors and investors will be crucial for the economy as the country battles drought and the ravages of a conflict that took the lives of an estimated 240,000 Afghans. The Taliban have promised safe passage out of the country for any foreigners or Afghans left behind by the huge airlift which ended when U.S. troops withdrew on Monday.

But with Kabul Hamid Karzai International Airport still closed, many were seeking to flee over land. Qatar's foreign minister said the Gulf state was talking with the Taliban and Turkey about potential technical support to restart operations at Kabul airport, which would facilitate humanitarian assistance and possibly more evacuations.

British Foreign Secretary Dominic Raab told the same news conference in Doha "we need to adjust to the new reality" in Afghanistan and said he would be talking with regional leaders about securing safe passage through third countries.

"Our immediate priority is...those remaining British nationals, and also the Afghans who worked for the United Kingdom and others who may be at the most risk," Raab said.

The Taliban's supreme leader, Haibatullah Akhundzada, is expected to have ultimate power over a new governing council, with a president below him, a senior Taliban official told Reuters last month. The supreme Taliban leader has three deputies – Mawlavi Yaqoob, son of the movement's late founder Mullah Omar, Sirajuddin Haqqani, leader of the powerful Haqqani network, and Abdul Ghani Baradar, one of the founding members of the group.

An unelected leadership council is how the Taliban ran their 1996-2001 government, which enforced a radical rule until it was ousted by U.S.-led forces. The Taliban have tried to present a more moderate face to the world since they swept aside Afghanisatan's U.S.-backed government last month, promising to protect human rights and refrain from reprisals against old enemies.

The Taliban have asked Afghan diplomats to stay in overseas posts for the time being, according to a source with direct knowledge of the move. The militant group had made clear there would eventually be change but also wanted to maintain a sense of continuity, the source said. But the United States, the European Union and others have cast doubt on such assurances, saying formal recognition of the new government – and the economic aid that would flow from that – is contingent on action.

The foreign minister of current EU president Slovenia told Reuters the bloc was "far from even tackling this question," which EU leaders might discuss at summits next month. Some EU states consider the Taliban a terrorist organisation. If the European Union – the world's biggest aid donor – decides to formally recognize the Taliban government, "aid is the leverage that the European Union has" in setting conditions, Anze Logar said.

On Wednesday, U.S. Undersecretary of State Victoria Nuland had said the United States would look at deeds not words.

"So they've got a lot to prove... they also have a lot to gain, if they can run Afghanistan, far, far differently than they did the last time they were in power," she said.

Economic collapse

In Kabul, "a real change has come into the city" resident Zahid Ullah said.

"The environment and peace is good but issues with wages since no one knows who is running the country. People are unemployed and searching for work." Humanitarian organisations have warned of catastrophe as severe drought and war have forced thousands of families to flee their homes.

Afghanistan desperately needs money, and the Taliban are unlikely to get swift access to the roughly $10 billion in assets mostly held abroad by the Afghan central bank. The new central bank head has sought to reassure banks the group wants a fully functioning financial system, but has given little detail on how it will provide the liquidity needed, bankers familiar with the matter said.

Afghanistan's economy is expected to collapse by 9.7% this financial year and 5.2% next year, Fitch said in a report. Foreign investment would be needed to support a more optimistic outlook, a scenario that assumed "some major economies, namely China and potentially Russia, would accept the Taliban as the legitimate government."

While the Taliban are cementing control of Kabul and provincial capitals, they are fighting with opposition groups and remnants of the old army holding out in mountains north of the capital. Senior Taliban leader Amir Khan Motaqi called on the rebels in Panjshir province to surrender, saying "the Islamic Emirate of Afghanistan is home for all Afghans."

Panjshir opposition leader, Ahmad Massoud, son of a former commander who fought against the Taliban in the 1990s, was unconvinced.

"Unfortunately, the Taliban have not changed, and they still are after dominance throughout the country," Massoud told CNN.