Thousands of people who fled Afghanistan were forced to return by the UK government before the Taliban re-took control - with calls mounted to bring them back.
Home Office figures show that there were 11,288 removals from 2004 to the end of last year - with 5,700 of these occurring since 2010.
In this period more than 7,200 were classified as 'enforced removals', government data reveals.
But analysis by European thinktank the ISPI suggests the real number could be even higher - saying 15,755 people sent back to Afghanistan by the UK between 2008 and 2020, the highest number in Europe.
Campaigners say those fleeing for their lives were "routinely" turned away, with asylum seekers "badly failed".
Immigration rights groups have called for those forced to leave to be allowed to return after the Taliban swept to power at the weekend, leaving hundreds of thousands fearing for their lives.
The Home Office says it is updating its guidelines and enforced returns have been paused in light of the collapse of the Afghan government.
Home Secretary Priti Patel has pledged to accept 20,000 people from Afghanistan, but just 5,000 in the next year, sparking heavy criticism as the crisis unfolds.
And groups which support asylum seekers warn that new legislation will criminalise desperate refugees based on the way they reach these shores.
Stabir Singh, chief executive of the Joint Council for the Welfare of Immigrants (JCWI) told The Mirror: "Britain has both a moral duty and the financial means to provide sanctuary to those who've fled danger.
"But sadly, our government routinely denies refuge to those whose lives are at risk.
"At JCWI, we have supported tens of Afghan refugees whose claims to asylum were initially refused.
"Just months ago, an Afghan client of ours was threatened with deportation despite the Home Office accepting he had been tortured by the Taliban. And sadly the new anti-refugee Bill going through parliament will make the situation worse.
"The government must urgently change course on refugee protection. It must grant protection based on need, not on method of flight, and grant immediate asylum to those whose lives are at risk – this includes the almost 3000 Afghans still awaiting asylum in the UK."
Bella Sankey, who heads human rights organisation Detention Action, posted on Twitter : "The UK Government must immediately release any Afghan nationals held in immigration detention and grant leave to remain to all those in the country.
"This should not be difficult and should be done immediately and without delay."
She added that those allowed to resettle in the UK should include those whose asylum applications were rejected, stating: "The UK has badly failed these people and put them in a life-threatening situation. It must use its best endeavours to bring them back."
According to Home Office figures, the number of Afghans removed from the UK has slowed in recent years, dropping to 49 last year.
This included 21 who departed after April, while the UK was subject to lockdown restrictions.
A year earlier there were 89 removals - down on the 1,181 in 2010.
Between 10,174 and the end of 2020 there were 10,174 asylum applications, with 1,275 lodged in the 12 months to the end of March.
According to analysis by the Italian Institute for Political Studies (ISPI) based on EU statistics, the UK leads the way in turning away people from Afghanistan.
It found that 15,755 were removed between 2008 and 2020, well ahead of second-placed Sweden with 9,970.
Matteo Villa, an analyst from the ISPI, wrote on Twitter : "Take a minute to remember what Europe * could * really have done
"Between 2008 and 2020, we (European nations) repatriated more than 70,000 Afghans. My thought goes to them."
Tim Naor Hilton, CEO of Refugee Action, told The Mirror: “In Afghanistan the world is witnessing how fast a whole population can be left desperately seeking safety.
"The importance of asylum has never been so clear. We believe most people in the UK would want their country to play its part in helping Afghans to find protection. But, 70 years after the UK signed the Refugee Convention, this Government is busy pulling up the drawbridge.
“The anti-refugee Bill currently going through Parliament would effectively end the asylum system and it offers no new routes to safety.
"Under the Bill, Afghans arriving in the UK to claim asylum would most likely be met with punishment, not protection, and potentially shipped off to the faraway islands for who knows how long to be “processed” in detention centres."
Mr Hilton continued: “Instead of whipping up hostility against those risking their lives to find shelter on our shores, we want the Government to build a refugee protection system that actually provides sanctuary.
"The extreme and nasty anti-refugee Bill must be thrown out and a long-term commitment for refugee resettlement made. In this way the UK will be able to protect those fleeting tomorrow’s crisis and not just today’s.”
The Home Office has said it is "closely monitoring" the situation in Afghanistan and said enforced returns have been paused.
A spokeswoman said: “We have been closely monitoring the situation in Afghanistan and due to the escalations this weekend are urgently updating our information and policies to inform asylum claims.
“We have in the meantime removed our country policy information, and enforced returns have been paused while we consider the situation.”
