The prominent Brexiteer, considered the favourite of the Conservative leadership race, has landed in hot water after ex-Tory Brian Coleman claimed that former London mayor Boris Johnson had a vicious outburst when he was briefed on the 2005 terror attacks, which took the lives of 52 people in the UK capital.

The former head of the London Fire and Emergency Planning Authority, Brian Coleman, has claimed that Boris Johnson burst out with a fiery rant during a 2011 briefing on the cost of the inquests into the 7/7 bombings when he was the mayor of London, The Mirror reports.

Coleman recalled that when he was telling Johnson that the Authority, the Metropolitan Police and Transport for London had to spend “a sizeable sum” on lawyers, the former mayor interrupted him with a rant against Tony Blair, who was the prime minister when the attacks took place: “I blame Tony Blair for all this. He started it with the Marchioness”. According to the former official, this was a reference to the investigation of the 1989 Thames collision between the Marchioness pleasure steamer and the dredger Bowbelle, which killed 51 partygoers.

Coleman pointed out that when the mayor’s communications chief Guto Harri noted that the London bombing inquests were for the families of the victims, Johnson replied: “F*** the families! F*** the families!”

“I was having none of this and snapped at Boris, “You didn’t have to write eight letters of condolence to families of your constituents or attend the funeral of 31-year-old Lee Baisden [a Fire Authority employee] who had been blown to pieces at Aldgate and comfort his poor widowed mother”, Coleman told the outlet.

However, Harri claimed that he didn’t hear Johnson say the F-remark, as Coleman claimed.

“It’s not the kind of thing he would say so I think it’s extremely unlikely”, Johnson’s former communications boss noted, adding that his account of a subsequent conversation was different.

Nevertheless, Coleman, who himself was excluded from the Conservative Party after an assault on a café owner, insisted that he stood by his story and told The Sunday Mirror that Johnson is “not suitable to be PM”.

“I’ve never written it down before but people need to know about this. That’s my only agenda”, Coleman claimed, adding that Johnson “was a poor judge of character” and slammed him for “many failed and pointless projects”.

The reports say that the Tory leadership favourite has not commented on the allegations.