Former PM Sir John Major has said he is "angry about the way the British people are being misled" by the campaign to get Britain out of the European Union.
He told Andrew Marr he feared people would vote to leave on the basis of information "known to be incorrect".
He highlighted claims by Leave figures Boris Johnson and Michael Gove that the UK sent £350m a week to the EU as an example of "deceit".
Mr Johnson stood by the figure and urged an end to "blue-on-blue action".
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In his most outspoken intervention to date in the referendum debate, Sir John insisted he was not personally attacking fellow Conservatives Mr Johnson and Mr Gove but he accused them of running a campaign that was "verging on the squalid".
And he described former London mayor Mr Johnson as a "court jester," who he suggested might not have the loyalty of Conservative MPs if he became party leader.
'Hungry python'
The former Conservative leader said: "They are misleading people to an extraordinary extent".
"They are feeding out to the British people a whole galaxy of inaccurate and frankly untrue information.
"And what they have not done is tell us what would be the position if we were to vote to leave," he told Andrew Marr.
He predicted "chaos" if Britain voted to leave in 23 June's referendum and claimed Britain would lose a "huge amount national income" through trade with Europe, adding: "These promises of expenditure on the National Health Service and elsewhere are frankly fatuous, they are a deceit."
He claimed the NHS would be "about as safe" in the hands of Mr Johnson, Justice Secretary Mr Gove and former Cabinet minister Iain Duncan Smith as a "pet hamster would be with a hungry python".
And he suggested Mr Johnson knew Britain's contribution to the EU, after a rebate and money back for farmers, was "about one third" of the £350m claimed on the side of his Vote Leave battle bus.
'Take back control'
But Mr Johnson told Marr the £350m figure was a "reasonable" one, arguing that, although some of it was returned by the EU, "this is money we cannot control," adding it could be spent on the NHS or other "one nation" priorities in the event of a Brexit.
He said Vote Leave was setting out "an agenda for the government to take back control" after leaving the EU - and the Remain campaign had no "long-term vision for the economy" if immigration continued at its current rate.
He predicted the UK's population could rise "inexorably", potentially as high as 80 million.
Sir John attacked Vote Leave's "depressing and awful" arguments on immigration, including the suggestion that 88 million Turkish people could "flood" into the UK if Turkey was given the right to join the EU.
"Turkey will not be in the European Union for a very, very long time, if ever, and the Leave campaign know that. That's the point - they know that," he said.
Mr Johnson hit back, saying: "Frankly, I don't mind whether Turkey joins the EU, provided the UK leaves the EU".
'Frustrating'
Pressed on his previous support for Turkey joining the EU, he said "that was back in the days when some of us thought that widening the EU would not mean this federalising, centralising, deepening process that we have seen".
"The EU has changed out of all recognition since people like me first started advocating Turkish membership," he added.
Quizzed by Andrew Marr about a new Vote Leave poster saying David Cameron cannot be trusted on immigration, Mr Johnson said it was "frustrating" the government was not meeting its manifesto commitment to reduce annual net migration to the "tens of thousands".
He said he had hoped Mr Cameron could address this in his EU renegotiation, but the PM "didn't get a sausage" from Brussels.
He also said it was "absolute nonsense" he was backing Brexit out of personal leadership ambitions.
"Obviously there is going to be a temptation by one side or the other to try to turn it into a personality-driven conversation.
"My view about the EU has changed but that is because the EU has changed out of all recognition."
In a tweet, Vote Leave chief executive Matthew Elliott said Sir John Major used to "get away" with personal attacks because "people sympathised with him" but he added: "Now they're so frequent he looks slightly mad."