UK security chiefs were warned in January that Salman Abedi was planning an attack in Britain, it was claimed last night.

According to a security source, the FBI told MI5 that Abedi was part of a North African Islamic State cell plotting to strike a political target in the UK.

The information came from a US investigation into Abedi and his links to terrorist groups in Libya. The Mail on Sunday has also been told that US security services put him on a terror watch list – used by agents to identify key suspects – in 2016.