The Government has deported three times as many teenagers to countries ravaged by war and poverty than ministers have previously admitted, figures seen by The Independent reveal.

Charities and politicians have warned the “life or death” decisions of whether to deport young people are being mishandled by a “callous” Home Office without a grip on the facts.

Despite spending their formative years in Britain, children granted temporary leave to remain in the UK as asylum seekers are often sent back to a country they have not lived in for years when they turn 18.

The Home Office says the young people sent away from the UK “no longer need our protection”.

Ministers had previously believed that just 151 former child asylum seekers had been removed after coming of age in 2014, but quietly issued a correction buried deep in parliamentary documents issued the day MPs went home for Easter.

The new statistics show that 445 18-year-olds who came to the UK as children were in fact sent back to the countries they flee from as soon as they come of age.

The change, part of a wider and previously reported revision of asylum data stretching back to February, means three times as many of the teenagers are being thrown out as previously thought.

Protest outside Home Office

Charities have warned the bungle is a reflection of an asylum system letting down young people.

“These children grow up here; often achieve well in school and then find themselves confused, frightened and abandoned by the country they thought would protect them, when they turn 18,” Anna Musgrave, advocacy manager at the charity told the Independent.

“The Government knows all too well that the asylum system is letting young people down and needs urgent reform to make sure that everyone gets a fair hearing.”

Research last year by the Bureau of Investigative Journalism identified worrying end destinations for some 18-year-old deportees: the Afghan conflict, the Syrian civil war, the Iraqi insurgency, and the failed state of Libya.

Turkey's two million Syrian refugees Show all 11 1 /11 Turkey's two million Syrian refugees Turkey's two million Syrian refugees There are already over 2.5 million Syrian refugees in Turkey, but their current camps can only hold 200,000 people ADEM ALTAN/AFP/Getty Images Turkey's two million Syrian refugees Turkish citizens protest a new deal, also criticised by human rights activists, which will see refugees who arrived in Greece after March 20 be sent back to Turkey AP Photo/Emre Tazegu Turkey's two million Syrian refugees An estimated 80% of Syrian refugee children already in Turkey are unable to attend school BULENT KILIC/AFP/Getty Images Turkey's two million Syrian refugees Refugee children beg for water near the Turkey-Syria border. Turkey has been accused of illegally deporting asylum-seekers back to Syria BULENT KILIC/AFP/Getty Images Turkey's two million Syrian refugees In Turkey, no-one from outside Europe is legally recognised as a refugee, meaning the 2016 deportations may not meet international legal standards for protecting vulnerable people BULENT KILIC/AFP/Getty Images Turkey's two million Syrian refugees A refugee child cries as she is searched by police at the Syria-Turkey border, where 16 refugees (including three children) have been shot dead in the last four months BULENT KILIC/AFP/Getty Images Turkey's two million Syrian refugees Many refugees are living rough on the streets of cities such as Istanbul or Ankara (pictured) ADEM ALTAN/AFP/Getty Images Turkey's two million Syrian refugees Turkish soldiers use water cannon on Syrian refugees BULENT KILIC/AFP/Getty Images Turkey's two million Syrian refugees Syrian refugees shelter from rain in the streets of Istanbul BULENT KILIC/AFP/Getty Images Turkey's two million Syrian refugees A derelict building housing Syrian refugees in Istanbul Carl Court/Getty Images Turkey's two million Syrian refugees Turkey houses around half of all the refugees who have currently fled Syria Carl Court/Getty Images

The Independent reported that an average of 100 Afghans a year were being sent back to their country, despite the ongoing security situation there and the Foreign Office advising against travel for UK citizens.

Tim Farron, the Liberal Democrat leader, told The Independent that the approach to the teenagers was “callous” and that they should be given a chance to continue.

“Throwing 18-years-olds out of the country and back to places that they fled in terror exposes an immigration system that is self-defeating and utterly callous,” he said.

“It is time we put compassion first and give these young people who have been educated here in the UK the chance to stay. We must never forget how desperate you must be to leave everything behind and flee for your life.”

Previous reports from February suggest that between 2007 and 2015 a total of 4,000 asylum seekers who came to the UK as orphans have been deported.

Don Flynn, director of the Migrants’ Rights Network, warned of “an administrative culture that has insufficient regard for the well-being of vulnerable young people”.

“It says something about the way the Home Office approaches these issues when they cannot even give a correct count of the numbers being expelled,” he told The Independent.

“The failure to get something as basic as the numbers being deported increases the worry that the Home Office is mishandling these procedures.”

Meanwhile, the charity Asylum Aid warned the Government needed to regain public trust after the blunder.

“It is worrying that the Home Office does not seem to have a handle on its own operations. The decision to remove an asylum seeker can be one of life or death, it is absolutely crucial that the proper care is taken with these matters so that the lives of young people are not put at risk,” a spokesperson said.

A Home Office spokesperson defended the Government’s record on the deportations. “The UK has a proud history of granting asylum to those who genuinely need it and every case is carefully considered on its individual merits,” she said.

“We take our international responsibility in cases involving children seriously and their welfare is at the heart of every decision made. Where people establish a genuine need for protection, or a well founded fear of persecution, we will grant refuge.