British intelligence services have reportedly intercepted communications from militants in Afghanistan indicating that UK jihadis have travelled to Afghanistan to join the Taliban.

Phone calls intercepted from war-torn Afghanistan have revealed jihadis with British accents living among the Taliban. It is believed that the British fighters smuggled themselves into the country following the withdrawal of American military personnel.

“We have received some intercepts of two British men, probably below 30, talking openly on mobiles,” a senior military intelligence source told The Sun.

“One had a London accent, what you might call a street accent.”

Another security service source reported that the government has “intermittent intelligence” indicating that British fighters have joined forces with the Taliban.

Colonel Richard Kemp CBE, who previously served as a commander of British forces in Afghanistan, said: “Many British and other foreign jihadists travelled to Afghanistan before and after 9/11 to fight there and, in many cases train, organise and then travel elsewhere for jihad.

“The more gains the Taliban makes, the more it will encourage jihadists to carry out attacks at home and also head for Afghanistan.

“If the country, or a large part of it, is permanently controlled by the Taliban it will again become a safe haven for terrorists as it was before 9/11.

“We are on the verge of a threat no less than that from [the Islamic State] at its height.”

In a statement, the government said that British Taliban militants “pose a very serious national security risk,” and that “The Home Secretary has a number of powers available to prevent the return of individuals who pose a national security risk to the UK.

“Those who do return must expect to be investigated by the police.”

It is believed that around 800 British nationals travelled to Iraq and Syria to join forces with the Islamic State, many of whom have been allowed to return to the country, often without being prosecuted for anything.

Last year it was revealed that Britain’s domestic counter-intelligence and security agency was aware of at least 43,000 suspected terrorists living in the United Kingdom.

There have long been concerns over the connections between UK-based terror cells and radical Islamists in Afghanistan, with then-Defence Secretary Gavin Williamson warning in 2018: “We consistently see terrorist groups operating here in Afghanistan, [and] evidence of their links back not just to the United Kingdom but to the whole of Continental Europe.”

With the country falling into chaos amid a bungled withdrawal by the Biden Administration, the British government has called on its citizens to evacuate Afghanistan. Some 600 British soldiers have been deployed back into the Islamic republic to help with rescue missions of the estimated 4,000 UK citizens in the country.

President Biden has also sent some 3,000 U.S. troops back into Afghanistan to launch similar evacuation efforts of Americans.

On Friday, the Taliban captured Lashkar Gah, the capital of Helmand province and the base of British military operations for much of the last two decades. Over half of the 457 British casualties of the Afghan war were in Helmand province.

Former government minister and Afghanistan veteran Johnny Mercer MP said of the withdrawal: “The political will to see through enduring support to Afghanistan has not been there, and a lot of people are going to die because of that, and for me that is extremely humiliating.”

Follow Kurt Zindulka on Twitter here @KurtZindulka