The battle to be the next prime minister turned increasingly ugly as contenders for the Tory crown rounded on each other.

International Development Secretary Rory Stewart seized on comments by ex-Brexit secretary Dominic Raab that he could close down Parliament as PM to force through a no-deal Brexit, branding the move potentially "illegal".

And Work and Pensions Secretary Amber Rudd said: "I think it's outrageous to consider proroguing Parliament. We are not Stuart kings."

Meanwhile Environment Secretary Michael Gove launched a pointed attack on former foreign secretary Boris Johnson and insisted he would be prepared to delay Brexit beyond October if a deal was within reach.

And Labour reacted furiously after Health Secretary Matt Hancock appeared to brand Jeremy Corbyn as an anti-Semite.

Mr Stewart was scathing about Mr Raab's assertion at private Tory leadership hustings that he would be prepared to temporarily shut down Parliament to make sure EU withdrawal happens on October 31.

Mr Stewart said: "All this talk about no-deal Brexit is a recipe for delay. It can't be done.

"And the the reason why Dom Raab is saying he is going to prorogue Parliament, in other words try to shut the doors on Parliament, is because the only way that they could try to get it through is by doing that.

"That would be illegal, if they did it for the express purpose of getting it through.

"It would be unconstitutional. It would be undemocratic. And it wouldn't work."

The comments came as Mr Gove moved to try to position himself as the liberal Tory leadership candidate who would be prepared to delay Brexit beyond October if a deal was close.

Speaking at an event in Westminster organised by The Spectator, Mr Gove said: "The critical thing to do is to recognise that if we're not 100% out by midnight on October 31 then we risk making that arbitrary deadline the determinant of what a good deal is.

"And I think if we're so close to the wire with what is, I believe, a better deal, then it would be right to take those extra few days or weeks in order to land it and to make sure that we're out."

Mr Gove also launched a thinly-veiled attack on Mr Johnson, who has previously insisted Prime Minister Theresa May's Brexit deal would make the UK a "vassal state".

The Environment Secretary said: "I think it demeans language to use words like vassal state.

"People use words like vassal state and treachery, traitor.

"You are not a traitor if you disagree with me about Europe."

In a warning to candidates promising to leave on October 31 "come what may", Mr Gove said that would risk forcing a general election before Brexit is secured.

"That would surely hand Downing Street to a Jeremy Corbyn government propped up by Nicola Sturgeon and the SNP," he wrote in an article for the Daily Mail.

"That would mean Brexit was lost, the future of our Union at risk and the levers of power handed to a Marxist."

Foreign Secretary Jeremy Hunt told the Tory hustings that Parliament would block a no-deal Brexit so the Tories needed a leader who could negotiate a better agreement.

Labour reacted with anger at remarks by Mr Hancock at the Tory hustings on Mr Corbyn.

According to a supporter of Mr Hancock, the Cabinet minister told colleagues at the gathering: "The Conservative Party has to get this right. If we don't, we could end up with the first anti-Semitic leader of a Western nation since the Second World War."

In response, shadow chancellor John McDonnell told the Press Association the comments were "a disgrace".

And a Labour source said: "This baseless political attack rings hollow from a minister in a party that has supported governments that actively promote anti-Semitic policies in Hungary and Poland and has spent the week wooing Trump - the man who refused to condemn neo-fascists in Charlottesville who chanted 'Jews will not replace us'.

"Numerous candidates in the Conservative leadership contest have been accused of racism, Islamophobia, homophobia and misogyny, one of whom may be the next prime minister."