A People’s Vote would throw the whole Brexit process “into chaos,” Michael Gove has insisted after London Mayor Sadiq Khan backed a second referendum on the final deal.

The Environment Secretary also made clear that, the UK having shown flexibility and compromise, the “focus” was now on what Brussels could offer.

In an article for the Observer, Mr Khan warned that the UK faced either a bad deal or no deal.

"They are both incredibly risky and I don't believe Theresa May has the mandate to gamble so flagrantly with the British economy and people's livelihoods,” he wrote.

Calling for another referendum, the London Mayor said: "This means a public vote on any Brexit deal obtained by the Government or a vote on a no-deal Brexit if one is not secured, alongside the option of staying in the EU.”

But Mr Gove said Mr Khan “wants essentially to frustrate the vote we had two and a half years ago. People voted clearly, 17.4 million people voted to leave the EU, and Sadiq is essentially saying: ‘Stop, let’s delay that whole process and throw it into chaos.’ That would be a profound mistake”.

Barry Gardiner, the Shadow International Trade Secretary, who has previously argued against a People’s Vote, warning it could lead to civil disobedience, again expressed coolness on the idea, saying a fresh referendum would throw the beleaguered Mrs May a lifeline.

"Calling for a second referendum is really giving her a lifeline because then she can say: 'Oh, if I can't get it through Parliament, I'll go back to the people.'"

The Scot said the first referendum had caused "real divisions" in the country.

"The challenge now is to try to heal society," he declared.

Mr Gardiner made clear Labour’s official position was not to take off the table the option of another referendum because “nobody knows what's going to happen over the next few weeks".

But Tory high command said Labour needed to rule out trying to delay Brexit.

“Across the country, Labour politicians are calling for a referendum rerun that would take us all back to square one,” stressed Brandon Lewis, the Conservative Chairman.

“Today, they have gone further and admitted that they want to keep the UK in the EU beyond March 2019; almost three years after the country voted to leave.”

He added: “While Labour are only interested in frustrating the process, the Conservatives have a plan for a deal which will deliver on the result of the referendum by taking back control of our laws, borders and money.”

But the Liberal Democrats, who back a People’s Vote, welcomed Mr Khan’s conversion.

Jo Swinson, the party’s deputy leader, said: "It shows that momentum is building to have a People's Vote on the deal."

Her colleague, Willie Rennie, who leads the Scottish Lib Dems, said Mr Khan had recognised that every day the promises made by the Leave campaign looked less and less believable.

“What’s more he’s speaking for the overwhelming majority of Labour members and Labour voters who don’t want to see Britain leave the EU,” insisted the Fife MSP.

He added: “Richard Leonard and Jeremy Corbyn need to recognise that the tide has turned. If they’re serious about protecting public services and our NHS, it’s time for them to speak out too.”

Meanwhile, Mr Gove insisted the Chequers Plan was the "right one for now".

Asked if it was a permanent proposal, he told BBC One's Andrew Marr Show: "Yes but there's one critical thing, a future prime minister could always choose to alter the relationship between Britain and the European Union.

"But the Chequers approach is the right one for now because we have got to make sure that we respect that vote and take advantage of the opportunities of being outside the European Union."

The Secretary of State said it would be up to the House of Commons in the future to "chart this nation's destiny" and decide what to do if EU law changed.

The leading Brexiteer pointed out: "I've compromised. I've been quite clear that some of the things that I argued for in the referendum passionately, as a result of Chequers, I have to qualify one or two of my views.

"I have to acknowledge the parliamentary arithmetic. The critical thing is making sure we leave in good order with a deal which safeguards the referendum mandate," he added.

Earlier, Liam Fox, who previously had put the chances of a no-deal at 60-40, admitted Brussels had been more conciliatory in recent weeks in the Brexit negotiations.

He told Sky News' Sophy Ridge On Sunday: "Over the last few weeks we have certainly heard more reassuring noises from the European Commission and some of our European partners.

"They have understood that Britain is serious that if we don't get a good deal we could end up with no-deal."

The Secretary of State said the Chequers Plan was a "reasonable, constructive way forward" in the Brexit talks.

"I do detect that there is a movement from the European Union towards getting a deal. It's by no means certain but it is moving in the right direction, although no-deal remains a possibility for which we have to prepare."

The Scot dismissed suggestions that extending Article 50, which takes Britain out of the EU, would help secure a good deal.

"Extending Article 50 until we have got an agreement is effectively allowing the European Union to dictate when Britain will leave the European Union itself," he added.