The United States has told Britain it will not insist on the death penalty for two alleged so-called Islamic State militants, part of a group dubbed The Beatles, who are suspected of beheading Western hostages.
It could open the way for Britain to cooperate with the US in the sharing of information for any potential case against Alexanda Kotey and El Shafee Elsheikh, who are in US custody.
The decision was revealed in a letter to Home Secretary Priti Patel from US Attorney General William Barr.
It is understood the move is seen as a welcome development by the Home Office.
According to the Associated Press, Mr Barr said in the letter: “I know that the United Kingdom shares our determination that there should be a full investigation and a criminal prosecution of Kotey and Elsheikh.
In March, the Supreme Court heard a challenge over the UK’s decision to share evidence about the two suspected so-called Islamic State terrorists without receiving assurances they would not face the death penalty in the US.
A panel of seven justices ruled that then-home secretary Sajid Javid’s decision to share evidence with the US was unlawful and was made at a time when UK authorities were coming under “political pressure from the US”.
Elsheikh and Kotey, who were caught in January 2018, are accused of belonging to a brutal four-man cell of executioners in Syria, nicknamed The Beatles because of their British accents, responsible for killing 27 captives.
Other members of the cell are said to include Mohammed Emwazi, the group’s ringleader, also known as Jihadi John, who was killed in a US air strike in 2015, while Aine Davis is in jail in Turkey for terror offences.
Kotey and Elsheikh, who were raised in the UK but have been stripped of their British citizenship, were captured by the Syrian Democratic Forces in January 2018.
Emwazi appeared in a number of videos in which hostages, including British aid workers David Haines and Alan Henning and US journalists James Foley and Steven Sotloff, were killed.
US officials have not announced any charges against Elsheikh and Kotey, but have spoken publicly about their desire to see members of the group face justice.
A Home Office spokesman said: “The Government’s priority has always been to protect national security and to deliver justice for the victims and their families.
“We continue to work closely with international partners to ensure that those who have committed crimes in the name of Daesh are brought to justice.”