The Taliban will be judged by its deeds rather than words, British Prime Minister Boris Johnson has said ahead of chairing an emergency G7 virtual meet to coordinate an international response to the Afghan crisis.

The Taliban seized power in Afghanistan on August 15, two weeks before the US was set to complete its troop withdrawal after a costly two-decade war. This forced Afghan President Ashraf Ghani to flee the country to the UAE.

Downing Street on Monday said that during the meeting on Tuesday, Johnson will call on the Group of Seven leaders from Canada, France, Germany, Italy, Japan and the US to continue to stand by the Afghan people and step-up support for refugees and humanitarian aid.

He is expected to urge international partners to match the UK's commitments on aid and the resettlement of those most in need in order to protect human rights and contribute to the stability of the region.

"Our first priority is to complete the evacuation of our citizens and those Afghans who have assisted our efforts over the last 20 years but as we look ahead to the next phase, it's vital we come together as an international community and agree a joint approach for the longer term," said Johnson.

"That's why I've called an emergency meeting of the G7 to coordinate our response to the immediate crisis, to reaffirm our commitment to the Afghan people, and to ask our international partners to match the UK's commitments to support those in need.

"Together with our partners and allies, we will continue to use every humanitarian and diplomatic lever to safeguard human rights and protect the gains made over the last two decades. The Taliban will be judged by their deeds and not their words," he said.

According to a Downing Street communique, the leaders of the world's seven major industrialised democracies are expected to reiterate their commitment to safeguarding the gains made in Afghanistan over the last 20 years in particular on girls' education and the rights of women and minorities.

Discussions are set to cover the ongoing collaboration on evacuation efforts at the Kabul airport and the longer-term work to secure a more stable future for Afghanistan and ensure any new government is inclusive and abides by its international obligations.

The meeting will take place by video conference and the NATO and UN Secretaries-General Antonio Guterres have also been invited to join the discussion.

It comes as the Taliban issued a stark warning that it would not entertain any suggestion of an extension to the August 31 deadline for the US-led NATO troops to exit Kabul.

The UK had hoped to persuade US President Joe Biden for such an extension in order to airlift its nationals and other eligible Afghanis out of the region.

Meanwhile, Johnson spoke to Biden on Monday ahead of the meeting to discuss the ongoing crisis.

They discussed the ongoing efforts by the UK and US to coordinate the rapid and safe evacuation of our nationals and those who previously worked with our governments from Kabul International Airport.

The leaders agreed to continue working together to ensure those who are eligible to leave are able to, including after the initial phase of the evacuation has ended, a Downing Street spokesperson said.

The leaders agreed on the importance of concerted diplomatic engagement to prevent a humanitarian crisis in Afghanistan.

They committed to driving international action, including through the G7 and UN Security Council, to stabilise the situation, support the Afghan people and work towards an inclusive and representative Afghan government, the spokesperson added.

Earlier, Johnson set out his five-point plan for addressing the risk of a humanitarian crisis in Afghanistan.

The plan has five parts: immediately helping those to whom we have direct obligations; protecting ourselves against any threat from terrorism; supporting Afghan people in the region through humanitarian and development assistance; creating safe and legal routes to resettle Afghans in need; and developing a clear plan for dealing with the new Afghan regime in a unified and concerted way.

The meeting of G7 leaders comes after the Prime Minister chaired a meeting of COBRA (Cabinet Office Briefing Rooms) on Monday, where the ministers discussed the latest situation on the ground.

As of Monday, the UK said it had secured the evacuation of almost 6,000 people out of Kabul since Operation PITTING began last week, which includes British nationals and their dependants, embassy staff and Afghan nationals under the Afghan Relocation and Assistance Policy (ARAP) programme.

The UK says it has already doubled the amount of humanitarian aid to the region, committing up to 286 million pounds with an immediate effect.

Last week, it announced a new bespoke resettlement scheme for around 20,000 vulnerable Afghans over the coming years.

The Taliban insurgents have stormed across Afghanistan, capturing all major cities in a matter of days, as Afghan security forces trained and equipped by the US and its allies melted away.

Thousands of Afghan nationals and foreigners are fleeing the country to escape the new Taliban regime and to seek asylum in different nations, including the US and many European nations, resulting in total chaos at Kabul airport and deaths.