G7 leaders will be under pressure to present a united front at an emergency summit on Afghanistan on Tuesday despite public divisions over the deadline to complete evacuations from the country by 31 August.

With the deadline to get out of Kabul looming, British prime minister Boris Johnson will chair online talks where, diplomatic sources told Reuters, G7 nations were expected to show unity on areas including whether to sanction or officially recognise the Taliban to avoid a humanitarian catastrophe and protect the human rights of vulnerable groups.

The talks come amid desperate scenes in Kabul, where countries including the US and UK are scrambling to get people out. Evacuations were being conducted on a “war footing” one Nato diplomat told Reuters on Tuesday. US special forces said on Monday they had retrieved 16 US citizens from a site two hours outside Kabul, and brought them back to the airport for evacuation processing.

White House aides have said they think the meeting could grow contentious, as US allies have looked on with disapproval at the tumultuous American drawdown.

Britain’s US envoy, Karen Pierce, said: “We want to start the process of developing a clear plan, so that we can all deal with the new Afghan regime in a unified and concerted way,” Pierce told Reuters. “We will judge the new regime by actions, not words.”

One European diplomat said: “The G7 leaders will agree to coordinate on if or when to recognise the Taliban. And they will commit to continue to work closely together.”

However, many US allies are still unhappy with Washington’s approach as Kabul fell on 15 August.

Communication between the White House and Downing Street during the crisis has appeared poor, with British ministers and officials repeatedly complaining that the Biden administration has not been clear with allies how long it plans to keep its military on the ground, and allow the evacuation to continue.

On Sunday, the US secretary of state, Tony Blinken, acknowledged that it had been a “powerfully emotional time for a lot of allies and partners”.

Officials in Washington confirmed that the UK has asked for the deadline for the Kabul evacuation to be extended, and that the US has been resistant.

However, in a frank admission about the dire situation in the Afghan capital, Sir Laurie Bristow, the British ambassador to Afghanistan, has made clear the Taliban would not tolerate western forces staying into September – a spokesperson for the group said on Monday this would cross a “red line” and “provoke a reaction”.

Speaking from Kabul, he said: “The signalling that we’re seeing from the Taliban, including earlier today, is pretty uncompromising that they want the operation finished by the end of the month.

“So I think it follows from that, that if the US and its allies were to try to push beyond that, then there’s at least a risk there, of us doing so in a much more difficult and less compliant environment.”

Johnson said in remarks released before the meeting that his “first priority is to complete the evacuation of our citizens and those Afghans who have assisted our efforts over the last 20 years”. But he also said the G7 had to “look ahead to the next phase”, when it would be “vital we come together as an international community and agree a joint approach”.

“Together with our partners and allies, we will continue to use every humanitarian and diplomatic lever to safeguard human rights,” Johnson said.

Tuesday’s talks will include leaders from the United States, Britain, Italy, France, Germany, Canada and Japan, plus Nato secretary general Jen Stoltenberg and UN secretary general Antonio Guterres.

Any decision by sovereign states to recognise the Taliban is a political act that will carry important consequence, including allowing the Taliban access to the foreign aid relied upon by previous Afghan governments. A 2020 agreement signed by the former Trump administration explicitly stated that the group “is not recognised by the United States as a state”.

The tool of recognition is “one of the most important remaining pieces of leverage that we have,” said Annie Pforzheimer, a retired US diplomat who served as the deputy chief of mission at the US embassy in Kabul from 2017 to 2018.

It would be “infinitely more powerful” if it was well coordinated and ensured that the new government was inclusive and recognised Afghanistan’s human rights commitments, she said.

Lord Ahmad, a UK junior foreign minister, is expected to stress the need for the Taliban “to respect human rights and fundamental freedoms” during an emergency session of the UN human rights council focused on Afghanistan on Tuesday.

Pierce said the G7 will take stock of the evacuation efforts and commit to coordinating closely on further steps, including security, humanitarian assistance and resettlement of refugees.

“We want to work together to convey the very important point that we don’t want Afghanistan to be a breeding ground for terrorism. We don’t want it to lapse into its pre-9/11 state,” she said.

UN agencies have already warned there could be food shortages as early as September without urgent aid funding, as delivery of first aid and other supplies is disrupted by the situation at Kabul airport.

On Monday, German foreign minister Heiko Maas said he would press G7 partners to commit additional funds for humanitarian aid. “I believe the G7 countries should live up to their responsibilities and find a response to mitigate the acute humanitarian hardship that’s already prevalent in the region and that will increase over the coming weeks.”

President Joe Biden said on Sunday that the US was already working with the Taliban to facilitate the evacuations, but that the Islamist group was “seeking legitimacy” in the longer term.

That meant it would need “additional help in terms of economic assistance, trade, and a whole range of things”, he said, but the international response – including potential sanctions – would depend on their actions going forward.

With Reuters