A person on the UK's 'no-fly' watchlist has reportedly managed to travel from Afghanistan to the UK on an evacuation report.
The incident is being considered a potential security breach after the individual arrived in Britain overnight, according to Sky News.
The arrival was said to have flown into Birmingham on a British military plane.
The government is set to announce the individual is not a 'person of interest' following checks and they will be free to go, Sky reports.
Britain's no-fly list is meant to be in place to stop people who potentially pose a threat from reaching the nation.
The report claims MPs were told today that five people on the watchlist attempted to leave Afghanistan with UK help, and four were prevented from flying - but one person made it to Birmingham.
The news reportedly emerged at a briefing for MPs by ministers and officials today as the UK effort to help Afghan refugees fleeing the Taliban continues.
A senior border force official also reportedly informed MPs a sixth more individual was intercepted in Frankfurt, and was blocked from continuing to the UK but his family were allowed to continue.
The broadcaster reports opposition MPs are concerned the incident is a security breach, but government sources claim it shows the watchlist is working.
The sources also emphasised to Sky people can be flagged on the "no-fly" list for a wide variety of reasons.
Kevin Foster, the Home Office minister, is reported to have told MPs on the call that while the UK must help people facing a threat from the Taliban, they must be "mindful" of people who risk the UK's safety.
A Government spokesperson told the Mirror: “There are people in Afghanistan who represent a serious threat to national security and public safety.
“That is why thorough checks are taking place by government, our world-class intelligence agencies and others.
“If someone is assessed as presenting as a risk to our country, we will take action.”
The report comes after a senior minister warned earlier today that people who wished to do the UK 'harm' had been attempting to get onto evacuation flights.
Armed forces minister James Heappey told BBC Radio 4's Today programme on Monday morning there are "people right now in Kabul trying to get onto British flights that we have identified in our checks as being on the UK no-fly list".
"There are people trying to take advantage of this process to get into the UK to cause us harm," he said.
Mr Heappey added: "Our troops have to have one finger on their trigger whilst in the other hand they're holding people's babies."
Scenes of chaos and heartbreak at Kabul's airport as scores of people try to flee the Taliban's Afghanistan takeover have attracted global concern.
Approximately 1,800 UK nationals and more than 2,200 Afghans who helped British forces are the "focus" of the Government's ongoing evacuation efforts from Afghanistan, Mr Heappy said.
The 4,000 people due to be evacuated next will join 6,000 which the Ministry of Defence has confirmed have already been flown out as part of the UK rescue mission.
On Monday morning, Mr Heappey said 1,821 people had been evacuated on eight flights in the last 24 hours, and nine more UK flights would leave Kabul in the next day.
He added that the numbers of people the UK wanted to evacuate from "Afghan civil society" had "grown significantly" in recent weeks, in an effort to resettle those who may face recrimination from the Taliban.
But the minister also warned the UK will not be able to evacuate everyone it hopes to.
Mr Heappey said he wished to assure people on the ground that an airlift was not the only route out of Afghanistan to the UK."
He added there was a "second phase" to the resettlement programme planned for when the UK withdraws fully from Kabul.
Afghans trying to escape the Taliban will be able to have resettlement claims processed at refugee camps or UK embassies in countries neighbouring Afghanistan in the near future.
Mr Heappey also said the Taliban had been an "effective partner" in marshalling crowds gathering outside Kabul's Hamid Karzai International Airport into separate queues for the US and UK evacuation flights.
Those repatriated under the rescue operation so far, called Operation Pitting, include embassy staff, British nationals, those eligible under the Arap programme and a small number of nationals from partner nations.
