David Cameron last night tore into Boris Johnson and Michael Gove over their conduct during the EU referendum.
Breaking his silence three years after he resigned, the former prime minister accused the pair of acting "appallingly" and "trashing the government".
He said they "left the truth at home" with claims that EU membership cost £350 million a week and that Turkey would join the bloc.
Cameron also accused Johnson of blundering in his short time at No 10. He cited "sharp practices" such as the decision to prorogue Parliament, and condemned the expulsion of 21 rebel Tory MPs.
Despite the Government saying Britain must be prepared for a No Deal Brexit, he said he opposed leaving without an agreement. Cameron made his explosive comments in an interview with The Times ahead of the publication of his memoirs next week.
Using the interview to open up about his personal anguish over his decision to call a referendum, he hinted that a second vote might be needed.
He spoke candidly about his family and his past but his criticism of Johnson and Gove is likely to attract the most attention.
In the memoirs, For The Record, which will be released on Thursday, Cameron apparently brands Gove, who is now Chancellor of the Duchy of Lancaster, 'mendacious' saying the referendum ruined their close friendship.
He tells how he sent Gove a text message saying "You are either a team player or a w*****" as he resisted being moved from education secretary to chief whip in 2014.
Although Cameron praises Johnson's 'good works' as London mayor, the memoir is understood to include a number of unhelpful anecdotes, including how he was late to emergency Cobra meetings during the London riots in 2011.
Johnson last night tried to play down the rift by insisting that "absolutely nothing" Cameron says "will diminish the affection and respect in which I hold him".
Speaking at an event in Rotherham, Johnson he added: "He has a very distinguished record and a legacy to be proud of."
Cameron's book threatens to intensify the Tory civil war as the Prime Minister prepares for his first party conference as leader in a fortnight's time.
In his interview with The Times, Cameron accused the Vote Leave campaign, which Johnson and Gove led, of misleading voters over the claim that Britain sent £350 million per week to Brussels that could be spent on the Health Service instead, and over the issue of whether Turkey could be stopped from joining the EU.
He said: "Over the issue of whether or not we had a veto over Turkey [joining the EU] and over the issue of the £350 million on the bus, I think they left the truth at home."
Cameron claimed Johnson decided to back the Leave campaign in the hope that it would boost his career. "Boris had never argued for leaving the EU, right?
"Michael was a very strong Eurosceptic but someone whom I'd known as this liberal, compassionate, rational Conservative ended up making arguments about Turkey [joining the EU] and being swamped and what have you.
"They were trashing the government of which they were a part. It was ridiculous."
Cameron also took aim at Johnson over his first weeks in Downing Street, suggesting he was pursuing the wrong Brexit strategy.
He said: "Of course, as a new prime minister I wished Boris well. I wanted him to get a deal from the EU that would have passed in the House of Commons. If that was to happen, I would have been elated.
"But clearly while he started down that road, the strategy has morphed into something quite different.
"Taking the whip from hard-working Conservative MPs and sharp practices using prorogation of Parliament have rebounded. I didn't support either of those things."
Gove declined to comment last night.