A British Islamic State fighter who is believed to have carried out a suicide bombing in Iraq was a former Guantanamo Bay detainee, according to reports.
The bomber, named by the group as Abu Zakariya al-Britani, is said to have detonated an explosives-filled vehicle in a village to the south of Mosul.
The 50-year-old, also known as Jamal al Harith or Jamal Udeen, was suspected of terrorism by the Americans but freed from the US detention centre in 2004 after lobbying by the British government.
He reportedly alleged torture and received £1 million in compensation from the Government after his release.
According to the BBC, the bomber was a Muslim convert born Ronald Fiddler.
Zakariya al-Britani turned to Islam in the 1990s and travelled to the Pakistani city of Quetta in 2001 for what he claimed was a religious holiday.
He has insisted he tried to enter Iran when the US invaded neighbouring Afghanistan, but was captured and imprisoned by the Taliban on suspicion of being a UK spy.
Around 850 individuals of national security concern have travelled to join the conflict, according to figures published by the Government last year.
Of those, just under half have returned to the UK and approximately 15% are dead.
A Foreign Office spokesman said: "The UK has advised for some time against all travel to Syria, and against all travel to large parts of Iraq.
"As all UK consular services are suspended in Syria and greatly limited in Iraq, it is extremely difficult to confirm the whereabouts and status of British nationals in these areas."