Taliban militants now in charge of Kabul have stepped up searches for people who worked with UK, US and Nato forces, according to a confidential United Nations document.
Fighters are going door to door and threatening to take family members hostage unless their targets surrender themselves.
Senior Afghan officials also told Britain's Daily Telegraph that they had been forced to go into "deep hiding" to avoid Taliban teams who are hunting for wanted members of Ashraf Ghani's ousted administration.
Their accounts and the UN document leaked to the New York Times contradict Taliban assurances that they would not seek revenge on members of the former government.
The manhunt has included searches of crowds at Kabul's international airport, where thousands are still trying to flee the country on evacuation flights.
The document from a group called the Norwegian Centre for Global Analyses, which provides intelligence to UN agencies, said there were reports the Taliban were working from a list of people they wanted to question and punish. The list included the locations of their targets.
Taliban had been going door to door and "arresting and/or threatening to kill or arrest family members of target individuals unless they surrender themselves to the Taliban", the report said.
Members of the Afghan military and the police, as well as those who worked for investigative units were most at risk.
Earlier this week former British Army officers told the Telegraph that hundreds of Afghan commandos from elite units were in hiding and on the run, trying to escape. The units were the Taliban's most feared adversaries and there are concerns their members will be hunted down and executed.
The document contained a letter dated August 16 from the Taliban to an unnamed counterterrorism official in Afghanistan, who had worked with US and British officials. The official has gone into hiding.
The letter instructed the official to report to the Military and Intelligence Commission of the Islamic Emirate of Afghanistan in Kabul. If not, it warned that the official's family members "will be treated based on Shariah law".
A former high-ranking counter-terrorism official, who spent years working with the British and Americans putting hundreds of jihadist terrorists into prison, said his life had been threatened by militants now released from jail in Kabul.
He went straight into hiding after the Taliban surrounded the capital, fearing the threat to his life was extremely grave. His neighbours have since reported that released prisoners have shown up to his front door on multiple occasions, heavily armed and attempting to break in.
Visits had got more frequent as the days had gone by, he said. Militants appeared to be visiting of their own accord, rather than on orders, suggesting a lack of hierarchy and control on the ground.
The official, who is in hiding with his 9-month-old baby, said that those searching have a list of prosecutors, judges and government workers to target, which contains detailed personal information. He suggested the militants had gained access to government databases and were using them to hunt down their enemies.
Another high ranking member of the previous government, who spoke to the Telegraph anonymously via contacts in the UK, claimed he had been targeted for his beliefs that girls should be educated.
When Kabul fell on Sunday, he was repeatedly visited and questioned by Taliban militants, without the threat of violence.
However, following the Taliban press conference on Tuesday, in which an amnesty was offered to all government officials, it was determined that the threat to his safety had in fact heightened, and he went underground. This official says his home has been visited 15 times in the past 72 hours, as militants ramp up their search for those they deem enemies and a threat to the formation of a new government.
"My house [has] now become probably their hourly point of search and my kids are deeply terrified," he said. "The moment they knock at the door all kids start crying. They think they will be killed."
Both officials said they did not qualify for asylum in the UK via the Afghan Relocations and Assistance Policy (ARAP) as they were never formally employed by Britain. Both are in touch with UK contacts who are attempting to push through emergency asylum applications via a crisis list.