Reilly was arrested by police at the scene of the explosion in the Giraffe restaurant in the £230 million Princesshay shopping complex in Exeter, Devon.

He suffered lacerations to his eye and some facial burning after a device he had on him partially exploded. Another device found in the vicinity of the restaurant did not explode.

Deputy chief constable Tony Melville, speaking just yards from the restaurant, said: "Witnesses described how a male entered a toilet in the restaurant shortly before an explosion was heard."

He said police and other emergency services went to the scene and the man was arrested in connection with the explosion.

Mr Melville said: "This male, who we now know is called Nicky Reilly, suffered serious facial injuries but these are not life threatening. He is currently in police custody undergoing treatment at a hospital."

Bomb disposal experts made safe two explosive devices which are now being forensically examined, said Mr Melville.

"After the arrest, police searched an address in King Street, Plymouth, linked to Reilly using armed officers from the tactical aid group."

He added: "Our investigations so far indicate Reilly, who has a history of mental illness, had adopted the Islamic faith. We believe, despite his weak and vulnerable state, he was preyed upon, radicalised and taken advantage of."

Mr Melville said the police knew Reilly travelled between Plymouth and Exeter using the bus service.