Story highlights Al-Harith reportedly carried out a car bombing in Iraq Monday

Blair said he was paid compensation by a subsequent UK government

London (CNN) Former British Prime Minister Tony Blair has defended his attempts to secure the release of a UK citizen from Guantanamo Bay after reports that the former detainee carried out an ISIS suicide attack in Iraq this week.

ISIS on its media affiliates claimed that Abu-Zakariya al-Britani -- a British citizen who initially went by Ronald Fiddler and later took the name Jamal Udeen al-Harith -- detonated a car bomb at an Iraqi army base southwest of Mosul this week.

While a spokesman for Prime Minister Theresa May said there had been no independent verification that the attacker was the former Guantanamo detainee, an official told CNN that UK intelligence services believe with "high confidence" that the bomber killed near Mosul was the former British inmate.

CNN affiliate Channel 4 has verified the identity of the man through a family member as al-Harith, a 50-year-old from Manchester.

Blair confirmed Wednesday that al-Harith was paid compensation by a subsequent UK government in 2010 for his time in the US detention facility, but did not confirm how much he was given.

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