Christian Aid is warning of a fresh humanitarian tragedy as Pakistan threatens to expel 1.4 million "undocumented" Afghan nationals by 1 November.
The development agency said that women, human rights defenders and anyone who worked for Western countries before the Taliban takeover are at risk of reprisals.
Christian Aid's Head of Asia Region, Ramani Leathard, said that the situation in Afghanistan has "deteriorated significantly" due to conflict, violence and "deep-rooted poverty".
She said that the prospect of a harsh winter only adds to the country's woes, and that many may attempt to reach the UK or EU countries.
"The forced return of already extremely vulnerable Afghans, who fled the country after the Taliban takeover, back to a country that is already grappling with hunger and drought, is a huge concern," said Leathard.
Christian Aid has warned that Afghanistan's economy is too fragile to cope with a large-scale influx of refugees and that the situation has been worsened by an earthquake earlier this month as well as cuts to international aid budgets.
It is calling on the UK to provide safe routes for vulnerable Afghan refugees and to put diplomatic pressure on Pakistan not to expel them.
It also wants to see an increase in funding for humanitarian work that supports Afghan refugees.
"The UK hosting next month's Food Security Summit is an opportunity for the international community to find solutions to Afghanistan's continuing hunger issues. Afghanistan must not be forgotten," said Leathard.
UNHCR, the UN's refugee agency, estimates that there are 3.7 million Afghan refugees in Pakistan, including 700,000 who fled after the Taliban takeover.
Pakistan has said that those who are not registered as refugees will be deported.
Ravina Shamdasani, spokesperson for the UN high commissioner for human rights, said, "We are very worried that those who are deported face a whole host of human rights violations including torture, arbitrary arrest and detention, severe discrimination, and lack of access to basic economic and social needs."
