Married British worker is missing in Afghanistan 'after being arrested at gunpoint by Taliban'
Grant Bailey has not been seen since Saturday when he was arrested by the Islamists during a security crackdown in Kabul.
It is feared the NGO worker in his 50s is being held in one of the capital's notorious prison complexes.
Mr Bailey, who is married and from southern England, had worked in Afghanistan for years and returned in September after the Taliban seized power.
The Foreign Office is desperately trying to locate him amid increasing fears for his safety.
A UK security source told the Daily Mirror Mr Bailey was arrested at gunpoint on Saturday.
They said: 'We were quite surprised he went back to Kabul after the Western withdrawal as the security situation there is obviously much worse.
'Added to that the Taliban government is making it very difficult for the few ex-pats working there, making it very difficult to travel.
'A lot of people are trying to get to the bottom of what has happened to him, where he is being held and under what charges.'
The Foreign Office told MailOnline: 'We are aware of the detention of a British national in Afghanistan and have been in touch with their family to support them.'
It comes after a dozen Afghan intelligence officers who spied for British troops say they have been left to the mercy of the Taliban despite being promised safe passage to the UK.
The 11 men and one woman worked for the country's National Directorate of Security (NDS), an agency disbanded by the Taliban after they seized the capital Kabul in August.
They are among thousands of Afghans and Britons still to be evacuated from the war-torn country.
The NDS officers conducted surveillance operations for British forces - including undercover missions for MI5 and MI6 to infiltrate groups like the Taliban and Al-Qaeda - with their primary role was to unearth terrorist plots in Afghanistan or against the West.
The operatives, whose ranks range from colonel to major general, are in hiding with their families. One officer was given an 'Eagle' award from British troops for valour on his secret missions.
Human rights groups claim more than 100 former NDS officers have been executed by the Taliban since August.
Susan Mateen, from the Afghan Council of Great Britain (ACGB) which is campaigning to bring them to Britain, said the suicide bomb attack at Kabul airport on August 26 had prevented the dozen NDS officers from being flown out. They have since been told that they need to cross into Pakistan before they can be rescued.
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'These 12 individuals served Britain and British counter terrorism missions loyally with many having 10 years or more of service, which in turn kept British troops safe and stopped terrorism to our shores,' said Ms Mateen. 'The British government has a duty to save them, but the UK has abandoned them to the Taliban.'
It was revealed earlier this month that the Taliban have beheaded or hanged dozens of prisoners and publicly displayed their bodies in extrajudicial killings.
A UN report said the militant group has also been recruiting child soldiers, and has been quashing women's rights since taking power in Afghanistan in August.
More than than 100 former Afghan national security forces and others have been killed since the takeover, the UN Human Rights Council heard.
Nada Al-Nashif, UN Deputy High Commissioner for Human Rights, said that in addition, at least 50 suspected members of the Islamic State-Khorasan Province - an ideological foe of the Taliban - were killed by hanging and beheading.
Al-Nashif said she was deeply alarmed by continuing reports of such killings, despite a general amnesty announced by the new Taliban rulers after August 15.
At least eight Afghan activists and two journalists have been killed since August, while the UN has also documented 59 unlawful detentions and threats to their ranks, she told the council in Geneva.
Concerned nations have pledged aid to the country, which made up a large part of its economy before the Taliban took over, but many are reluctant to send funds unless the Taliban agrees to a more inclusive society.
Meanwhile, reports from Afghanistan have told harrowing stories, such as parents being forced to sell their children to survive, and droughts forcing people from their homes.
The UN has warned that more than half of Afghanistan's population faces starvation this winter, a problem compounded by the fact that many aid agencies fled the country as the government collapsed and international aid dried up.
International charity Save the Children has called on governments to make urgent exemptions to existing counter-terror and sanctions policies, to allow for the delivery of lifesaving humanitarian aid.