Thousands of people were still crowding around Kabul airport on Wednesday in the hope of getting an evacuation flight out of Afghanistan, videos on social media showed.

Video footage showed hundreds of Afghans waiting in a moat outside the airport grounds - some standing in water up to their waists.

One man is seen on video climbing up the wall of the moat but is pushed back by two soldiers.

Countries have started to pick up their evacuees from other locations and bring them into the airport due to the chaotic situation around the airport entrances.

Two people on a US evacuation list said they were called to a location in the city and taken from there to the airport in an armoured convoy.

Taliban deputy leader Mullah Yaqoob assured Afghans they would be free to leave the country in the future.

"If they want to go abroad for jobs or to improve their lives, they can apply later for passports, get visas and leave the country through legal channels," Yaqoob said in an radio interview broadcast on Tuesday evening.

No one would stop them, he said. Leaving the country hurriedly and chaotically was creating a problem for all sides, he added.

Yaqoob maintained however that the majority of people at the airport simply wanted to go abroad "for their fantasies," rather than to flee Taliban rule.

After all, he pointed out, high-ranking representatives of the previous government were still living in the country and had been granted an amnesty.

The window of opportunity for military evacuations from Afghanistan is closing fast.

US President Joe Biden is sticking to plans for the withdrawal of US troops to finish by August 31, and was not swayed by pleas from European allies on Tuesday to allow more time for evacuations from Kabul airport.

Earlier this year, NATO allies said they would follow the US lead in ending their operations in Afghanistan.

If US troops leave Kabul airport, and with the Taliban in charge of the country, the safety of the facility cannot be guaranteed for further evacuations.

A Taliban spokesman clarified when asked by dpa that Afghans without documents authorizing them to leave would not be allowed to gather near the airport.

The US evacuation was "on a pace to finish by August 31," Biden insisted on Tuesday evening. Germany's foreign minister, however, had earlier said there would not be enough time to fly out everyone in need.

A letter sent late Wednesday by the German embassy in Kabul to their citizens in Afghanistan said Germany was still planning Bundeswehr evacuation flights as well as flights from Kabul to other countries run by allies.

Further concrete measures to facilitate the departure were also being examined, the embassy wrote.

Diplomatic sources have hinted in recent days that once the evacuation flights have ceased, those still needing to be evacuated may be able to leave Afghanistan by land and then flown to Europe from one of its neighbouring countries.

Both border crossings to Pakistan are currently open but Afghans need visas to enter.

dpa