Aine Leslie Davis, a member of the ISIS fighter group known as the Beatles, was detained in London on terrorism charges, London police said on Thursday.
Davis is in custody and will appear in court on Thursday, August 11, the report said.
He was detained the day before at one of the London airports after he arrived in the country from Turkey, where he was also convicted on terrorism charges a few years ago.
A group of four militants, nicknamed The Beatles for their English pronunciation, became known in connection with the executions of captives, including American journalists who were beheaded while filming what was happening on camera.
The leader of the Beatles, Mohammed Emwazi, nicknamed Jihadi John, was eliminated in Syria in November 2015. Another executioner, Briton Alexandra Kotey, pleaded guilty to involvement in the murders of Americans and other hostages from Western countries at a trial in the United States.