Sir John Major has attacked Boris Johnson and Michael Gove as "the gravediggers of our prosperity", in a last minute bid to persuade voters to choose to remain inside the EU at tomorrow's referendum.
The former Conservative prime minister said Vote Leave was guilty of behaving in a "grotesque" manner during the campaign.
Speaking alongside David Cameron and former Labour deputy leader Harriet Harman in Bristol this morning, Sir John said Gove and Johnson had been "raising unreasonable fears about migration and security in this country".
He added: "If our nation does vote to leave tomorrow, we must respect their decision. But if they vote to leave on the basis of half truths and untruths and misunderstandings then pretty soon the gravediggers of our prosperity will have some very serious questions to answer, they will have to account for what they have said and done."
Standing infront of Cameron, Sir John also put up a strong defence of his Tory successor. "I think the prime minister has fought an extremely brave campaign in very difficult circumstances," he said.
"He has put facts before our nation. He has warned of the dangers and that is his duty as prime minister. He can not ignore the dangers that we face. It is his responsibility to put those dangers before people."
"In return for doing that, he has faced a a great deal of opposition and sometimes abuse from people, who frankly. we might have expected better from."
Sir John said far from running "Project Fear", the 'Remain' campaign had been running "Project Information".
Yesterday, Johnson said he would apologise if the UK economy crashes as a result of Brexit - but insisted that would not happen.
Today, Gove is under fire comparing economic experts warning about the fall-out of Brexit to the Nazis who orchestrated a smear campaign against Albert Einstein in the 1930s.
Lord Sugar, who supports the 'Remain' campaign, has been called “racist” and “ridiculous” for saying a MP who supports Brexit should not “tell us British what we should do” because she is originally from Germany.