Nicki Reilly
©Devon and Cornwall Police/PA
CCTV image of Nicky Reilly, who has been named by police as the man arrested in connection with an explosion in Exeter.

Counter-terrorism officials believe a man who walked into a restaurant in Exeter at lunchtime yesterday and tried to explode a homemade bomb that could have caused serious injuries had been targeted for radicalisation by extremists.

The man was named as Nicky Reilly, 22, who officials believe has a history of mental illness and had converted to Islam. No one was hurt in the incident apart from Reilly, who suffered serious injuries to his face which are not thought to be life threatening.

Devon and Cornwall police were joined in the investigation by Scotland Yard's counter-terrorism command and MI5. Senior sources said the devices used were "viable" and could have caused significant harm. One said: "We're talking about more than a battery and bits of wire."

One improvised explosive device went off in the toilet of an Exeter branch of the restaurant chain Giraffe, injuring Reilly. Another unexploded device was found close by, providing investigators with clues as to who constructed them and how they were made.

Armed police last night raided a house in Plymouth where Reilly is believed to have lived. They found material there and removed items.

Toby Melville, deputy chief constable of Devon and Cornwall police, said: "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."

Melville said the police knew Reilly travelled by bus between Plymouth and Exeter yesterday. He said police were releasing his photograph because they wanted anyone who saw him yesterday, or could help the police track his movements over recent weeks, to contact them.

The nature of the incident led one source with knowledge of the thinking of senior counter-terrorism officials to describe the events as "amateur hour".

But the belief that Reilly may have been radicalised and the initial view that the device had potential to cause serious harm to others led to the investigation being intensified. Recently officials believe an attempt was made to radicalise another vulnerable man in the West Country, an area thought unlikely to be a terrorist target.

Police refused to confirm reports from some witnesses that nails were seen near the scene of the blast.

About 15 customers and staff were evacuated from the restaurant, described as part of a family friendly chain, after the explosion.

Exeter city centre was sealed off for hours and police invoked counter-terrorism powers giving them authority to stop and search people.