RUTH Davidson has renewed her public feud with Boris Johnson over Brexit, flatly contradicting his latest boast about the financial benefit of leaving the EU.

The Scottish Tory leader repeatedly refused to accept Mr Johnson’s claim that the infamous bus poster saying Brexit could mean £350m a week for the NHS was an “underestimate”.

In an interview with The Guardian, the Foreign Secretary said the UK’s gross weekly contribution to the EU would rise to £438m by the end of the Brexit transition period.

He said: “There was an error on the side of the bus. We grossly underestimated the sum over which we would be able to take back control.”

Accepting that was a gross figure, not a net figure that factored in money received from the EU, he nevertheless said half the sum could still be put into public services.

“As and when the cash becomes available - and it won’t until we leave - the NHS should be at the very top of the list,” he said.

However in an interview with ITV Border, Ms Davidson, who clashed with Mr Johnson in a Wembley debate on the eve of the EU Referendum in 2016, rejected his arithmetic.

Asked if he was lying - a charge Ms Davidson has previously levelled against Brexiteers - she did not dismiss the idea.

Instead, she said: “Well, look, he’s a member of the cabinet and he gets to see the Treasury’s books. I’m not a member of government and I don’t. But my understanding from as many economists and government watchers that were there at the time was that I was correct in what I said when I was on the stage at Wembley debating against it.”

Asked “So he was lying then and he’s lying now?”, Ms Davidson replied diplomatically: “Like I say, I can only take the analysis that I’ve seen, that I’ve seen from economists around the world, and we believed in the arguments that we were putting forward for remain.”

During the EU referendum, a bus used by Vote Leave, which included Mr Johnson, bore the slogan: "We send the EU £350 million a week - let's fund our NHS instead."

However this failed to include a £75m rebate from the EU.

The head of the UK's statistics watchdog called it “a clear misuse of official statistics”.

Pro-EU Tory MP Anna Soubry said Mr Johnson had to “man up” and stop “conning people”.

She told the BBC’s Daily Politics Show: “What I do know is that this is not going to be additional funds that will go to the NHS - and that was an important part of the trick that was played on the British people.

"Boris is being irresponsible to continue to con people in this way. He should be honest about the challenges that Brexit poses to our country.

"This is grown up, this is proper stuff, he's got to man up to the position he holds."

Labour accused Mr Johnson of returning “to the scene of his previous crimes”.

Shadow Brexit secretary Sir Keir Starmer accused him of having “no shame”.

Eloise Todd, of the anti-Brexit Best For Britain group, said: “This is a yet another untruth from Boris, a man who has become so obsessed with the lie he slapped on the side of the bus.”