Afghanistan's new Taliban rulers struggled to keep the country functioning on Wednesday after the final withdrawal of US forces, with foreign donors alarmed about an impending humanitarian crisis.

Two weeks since the Taliban's sweep into the capital Kabul brought a chaotic end to 20 years of warfare, the Islamist militant group has yet to name a new government or reveal how they intend to govern.

In an administrative vacuum, prices have soared and crowds have gathered at banks to withdraw cash.

While heavily-armed fighters have imposed control on Kabul, Taliban officials were grappling with keeping banks, hospitals and government machinery running following the end of a huge airlift of foreigners and Afghans who had helped Western nations during the international intervention.

Qatar's Al Jazeera television reported that Qatari technical experts had arrived in Kabul at the Taliban's request to discuss resuming operations at the city's airport, currently inoperable.

The foreign minister of neighbouring Pakistan, which has close ties to the Taliban, said he expected Afghanistan to have a new "consensus government" within days.

Meanwhile, people fearful of life under Taliban rule rushed to its borders in a bid to escape an uncertain future.

And in Panjshir province, members of local militias and remnants of former military units were still holding out under the leadership of Ahmad Massoud.

Senior Taliban leader Amir Khan Motaqi called on them to put down weapons and negotiate an end to the hostilities.

"The Islamic Emirate of Afghanistan is home for all Afghans," he said in a speech.

The Taliban have declared an amnesty for all Afghans who worked with foreign forces during the war that started when they were ousted from power in 2001 over their refusal to hand over al Qaeda leader Osama bin Laden after the Sept. 11 attacks.

Taliban leaders have called on Afghans to return home and help rebuild. They have promised to protect human rights in an apparent effort to present a more moderate face than their first government, which enforced radical Islamic law, including banning women from education and employment.

PRICES SOAR

But the more immediate concern for them now is staving off economic collapse. 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.

Long lines formed at banks in Kabul as people tried to withdraw cash and prices in the bazaars have soared. The currency is sinking and inflation rising, while many offices and shops remain shut.

"Everything is expensive now, prices are going up every day," said Kabul resident Zelgai.

The Taliban have ordered banks to re-open but strict weekly limits on withdrawals have been imposed.

Outside the capital, humanitarian organizations have warned of impending catastrophe as severe drought has hit farmers and forced thousands of rural poor to seek shelter in the cities. But foreign donors are unsure about whom to speak to.

Taliban officials have said the problems will ease once a new government is in place, and have appealed to other countries to maintain economic relations.

A new central bank chief has been appointed but bankers outside Afghanistan said it would be difficult to get the financial system running again without the specialists who joined the exodus out of Kabul.

"I don't know how they will manage it because all the technical staff, including senior management, has left the country," one banker said.

LEFT BEHIND

More than 123,000 people were evacuated from Kabul in the US-led airlift after the Taliban seized the city in mid-August but tens of thousands of Afghans at risk remained behind.

With Kabul's airport out of action, efforts to help Afghans fearful of Taliban reprisals focused on arranging safe passage across the nation's borders with Iran, Pakistan and central Asian states. 

At Torkham, a border crossing with Pakistan just east of the Khyber Pass, a Pakistani official said: "A large number of people are waiting on the Afghanistan side for the opening of the gate."

The Taliban are talking with Qatar and Turkey over how to run Kabul's airport, France said, but it could take days or weeks to finalise negotiations. Uzbekistan's border with northern Afghanistan remained closed.

Britain and India held separate talks with Taliban officials in Doha amid fears that up to half a million Afghans could flee. 

The UN refugee agency UNHCR said on Wednesday Afghans have so far largely stayed within Afghanistan and so far only small numbers had fled to neighbouring countries. It called for $300 million in international funding for the humanitarian emergency.

Washington said it would use its leverage, including access to the global marketplace, over the Taliban as it seeks to get the remaining Americans and allies out of Afghanistan.

The Taliban also said it had surrounded forces in Panjshir, the only province still resisting its rule, and it called on them to negotiate a settlement. Taliban leader Motaqi urged the fighters to lay down their weapons.

Some Taliban leaders mocked the United States.

"Your power is gone, your gold is gone," Anas Haqqani, who has emerged as one of the group's most prominent leaders, said on Twitter.

Haqqani posted a photograph of himself holding discarded prison shackles as he toured Bagram prison, where he spent years kept in solitary confinement by US forces.