MANCHESTER - Britain's MI5 intelligence service launched an internal inquiry on Monday into whether vital clues were missed in the run-up to the Manchester suicide bombing, as police arrested another man in connection with the attack.

The developments come a week after 22-year-old Salman Abedi, a British-born university dropout of Libyan origin, detonated his device outside a pop concert by teen idol Ariana Grande, killing 22 people.

A 23-year-old man was arrested in the southern coastal town of Shoreham-by-Sea, more than 400 kilometers from Manchester on Monday over the attack claimed by the Islamic State group.