FBI warned MI5 in January that the Manchester bomber was planning an attack on Britain

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.