David Cameron and the Conservative 'Remain' campaign must stop "lashing out", a leading Brexit Tory has said.
Steve Baker has accused the pro-EU camp in his own party of having been "reduced to fear, uncertainty and doubt".
The backbench Tory MP told BBC Radio 4's Today programme: "A full frontal assault with due warning is fine, but the dagger in the heart inserted from the back through whispering in dark corridors is not ok."
And warned the divisions in the party would be hard to heal if either side followed a "scorched earth policy" in the referendum.
"The 'Remain' campaign have realised they are losing the arguments, they are painted into the corner and are lashing out at individuals," he said.
Baker, the co-chair of the Conservatives for Britain group, said the reaction to Boris Johnson comparing the EU to Hitler's attempt to occupy Europe had beeb "hysterical".
"Any reasonable historical catalogue of efforts to unite Europe politically will include events of the of the first half the 20th century," he said.
However Baker said he would not have made the comparison himself. "Personally I wouldn’t bother using the 'H' word," he said.
Writing for Conservative Home, Baker added: "There have also been intolerable media smears against our leading figures and their families.
"It is a dark day indeed when Conservatives believe that the centre is behind such vicious briefing."
Lord Heseltine has said Johnson has behaved "irresponsibly and recklessly" for talking about Hitler. The former Tory deputy prime minister said it showed the former London mayor lacks the “judgement” to lead the Conservative Party
Yesterday the Tory civil war over Europe continued as Iain Duncan Smith claimed key reforms had been “jettisoned” from the Queen’s Speech to avoid upsetting some voters.
The former Work and Pensions Secretary said that Cameron had watered down or junks bills in a “helterskelter pursuit” to win the EU referendum.
And Dunan Smith said Heseltine was “a man of the past who should stay in the past.”
He told Sky News that it was time to "cut the name calling because this is childish and the public are tired of it".