An Islamic convert with a history of mental illness was slightly injured by his own bomb in an explosion at lunchtime in a busy restaurant in Exeter on Thursday, police said.

Nicky Reilly, 22, was arrested and taken to hospital after the small explosion in a branch of the family-orientated Giraffe restaurant chain in the centre of Exeter.

Although limited in scope, the attack was a reminder of earlier bombings and attempted bombings in Britain, given the arrested man's Islamic links.

Reilly was the only person injured in the latest attack, and little damage was reported from the explosion in the restaurant's toilets. Police later discovered and disarmed another device nearby.

"Our investigations so far indicate Reilly, who has a history of mental illness, had adopted the Islamic faith," said Tony Melville, deputy chief constable of Devon and Cornwall police.

"We believe, despite his weak and vulnerable state, he was preyed upon, radicalised and taken advantage of."

The blast happened shortly before 1 p.m. at the Giraffe restaurant in Exeter's Princesshay shopping centre.

Police said Reilly suffered cuts to his eyes and burns to his face, but his injuries were not life threatening.

"There was a very small explosion, nobody was injured except the person who caused the explosion," said Juliette Joffe, a Giraffe director in London. "There was very minimal damage, everyone has been evacuated quickly and efficiently."

She said the restaurant would have been "pretty full" at the time.

Police said they had found two other small devices near the restaurant and defused them. The city centre would remain closed while officers carried out detailed searches.

Security services say they have foiled numerous bomb plots in England since the September 11, 2001 attacks on New York and Washington - including plans to blow up transatlantic airliners in August 2006 using liquid explosives.

Four Islamist suicide bombers killed 52 people and injured hundreds of others when they exploded their home-made bombs on three underground trains and a bus at rush-hour in London on the morning of July 7, 2005.