A suspected suicide-bomber allegedly received a text message of encouragement as he set off to explode a device believed to be a nail bomb in a restaurant in an Exeter shopping centre.

Nicky Reilly, 22, who has been arrested in connection with the incident, had also come to the attention of MI5 before the alleged attack, security sources confirmed last night.

Armed police investigating the alleged bombing attempt yesterday arrested two men at an open-air café in the centre of Plymouth.

Shoppers and workers in the city, where Mr Reilly lives, were moved away from the area as police surrounded the two men, who were sitting at a table with a child in a pushchair.

Bystanders said that both men, said to be of Mediterranean or Asian appearance, were searched and put into sterile paper suits before being placed in unmarked cars. Police said later that one man was under arrest and the other was helping inquiries.

Forensic science officers spent yesterday examining the mobile phone, landline and computer used by Mr Reilly, a Muslim convert who also uses the name Mohammad Rasheed.

Neighbours claimed that Mr Reilly, who has a history of mental illness, had been radicalised at a takeaway food shop near his home. Twenty officers from the Metropolitan Police’s Counter-Terrorism Command have been sent to assist the Devon and Cornwall force’s investigation.

A source close to the inquiry told The Times that two devices seized in Exeter on Thursday were “viable” firebombs made of sodium hydroxide, paraffin and strips of aluminium foil. Reports suggest they may also have contained nails.

Mr Reilly suffered severe cuts to his face when one device exploded in the lavatories at the Giraffe restaurant. Police sources said that the bombs were volatile and could have been detonated by shaking.

Security sources confirmed last night that MI5 had a “trace” for Mr Reilly on its records as a result of information gleaned about his views, but he was not under investigation.

To his family and neighbours, Mr Reilly, who is 18st and well over 6ft, is a shambling, introverted 22-year-old “child in a man’s body”. Senior police officers said that he had been “taken advantage of” by Islamic extremists.

Worshippers at Plymouth’s two mosques were shocked that the unemployed man apparently injured himself with a home-made bomb.

Tony Melville, Deputy Chief Constable of Devon and Cornwall, said: “We believe that despite his vulnerable state he has been preyed upon, radicalised and taken advantage of.” Alli Turner, 17, a trainee youth worker and regular visitor to the flat where Mr Reilly lives with his mother, Kim, his stepfather, Phil Dinner, and two half-brothers, said that Mr Reilly was on his computer “24/7” and had few, if any, friends.

He said: “I knew he was into Muslim stuff because he changed his wallpaper on his computer to a picture of the Twin Towers. I never really asked him about it. I didn’t think it was my business.

“He changed his name to Mohammad about four years ago but his family and English people were allowed to carry on calling him Nicky. Someone must have brainwashed him into doing this thing.”

He added that Mr Reilly would watch videos of the September 11 attacks over and over again and had tried to kill himself several times.

Omar Siddiqui, the president of the Islamic Society at Plymouth University and a friend of Mr Reilly’s, said: “I cannot imagine anyone being radicalised in Plymouth and if anyone has taken advantage of this guy, it is quite sick.”

Sylvia Bellamy, a former councillor who has known Mr Reilly for years, said: “I don’t think he could do this on his own. He would follow like a little lamb.”

Worshippers arriving at the Islamic Centre, where Mr Reilly occasionally worshipped, said that many were staying away from Friday prayers because of what had happened.

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