Police searched a home in southeast England on Wednesday as part of an investigation into reports a British man was responsible for a suicide bombing in Syria.
The BBC named the bomber as 41-year-old Abdul Waheed Majid from Crawley in West Sussex, between London and the coastal town of Brighton.
He reportedly carried out a suicide truck bombing on February 6 as part of an attack by rebel fighters on the jail in the divided northern city of Aleppo.
Rebel fighters are held in the prison.
Police officers were searching a house in Martyrs Avenue in the Langley Green area of Crawley.
The Foreign Office said it could not confirm the identity of the bomber, who was reportedly known by the jihadist group al-Nusra Front as Abu Suleiman al-Britani, nor that a Briton was involved.
"We are aware of these reports but we cannot confirm them," a Foreign Office spokesman said, noting that Britain has no consular presence in Syria.
In Crawley, neighbours said the two-storey, end-of-terrace property being searched by police was previously home to a notorious child murderer, Roy Whiting, who killed eight-year-old Sarah Payne in 2000.
But they expressed surprise that the current resident might be involved in the conflict in Syria.
Neighbour Nita Bateman, 55, said the man was a "pleasant chap" in his 40s who helped other people on the street, and she believed he had been born nearby.
"You would never have a bad word to say about him - he was just a pleasant chap.
"I would say I'm shocked, but you just don't know what goes on behind closed doors," she said.
The International Centre for the Study of Radicalisation at King's College London estimates that between 200 and 366 British nationals have gone to Syria to fight.
A senior police officer warned last month that anyone returning to Britain from Syria risked being arrested.
