Foreign ministers from the G7 countries on Thursday urged the Taliban to provide safe passage for those trying to flee Kabul, in the group's first formal statement on the crisis.

The ministers "called for the Taliban to guarantee safe passage to foreign nationals and Afghans wanting to leave", according to Britain's foreign office.

G7 countries are "continuing efforts to do everything possible to evacuate vulnerable persons from Kabul airport", they added.

The meeting was chaired by British foreign minister Dominic Raab, who is under fire at home for reportedly being on holiday and "unavailable" to make a phone call to his Afghan counterpart as the crisis unfolded.

The G7 leaders said they were "deeply concerned by reports of violent reprisals" and "discussed the importance of the international community providing safe and legal resettlement routes".

They agreed "to seek to secure an inclusive political settlement, enable life-saving humanitarian assistance and support in Afghanistan and the region, and prevent any further loss of life in Afghanistan and to the international community from terrorism," added the statement.

Taliban fighters were at checkpoints around Kabul's airport on Thursday as concerns built they were blocking Afghans from reaching evacuation flights.

Tens of thousands of people have tried to flee Afghanistan since the hardline Islamist militants swept into the capital on Sunday, as US-led forces withdrew after 20 years in the country.