EIGHTY Labour MPs have told Jeremy Corbyn to secure a guarantee of a second referendum in any Brexit deal he reaches with Theresa May.

A letter signed by the MPs, including shadow ministers, was sent to Mr Corbyn and members of the shadow cabinet on Saturday and states that a public vote should be the "bottom line" in the negotiations.

The letter warns any concessions secured in the cross-party talks - which have so far failed to produce a breakthrough - cannot be guaranteed, meaning a referendum is a necessary safeguard.

May reached out to Corbyn last week after MPs again rejected the draft withdrawal agreement she negotiated with EU partners.

Labour insiders predict the talks will come to nothing, but supporters of another referendum believe Corbyn should make a public vote his top priority.

The letter by his own MPs said: "Theresa May has been clear that the legally binding part of the Brexit deal, the Withdrawal Agreement, cannot be renegotiated.

"This means that the only concessions Labour could obtain will be non-binding assurances about the future relationship. Any future Tory prime minister could simply rip up these 'guarantees' after Theresa May leaves office, and it is the stated aim of the vast majority of Tory MPs to do precisely this.

"The only way to guarantee jobs, rights and protections - and Labour's reputation with its membership and the electorate - is to support a confirmatory public vote on any option which is agreed by Parliament, which will put additional pressure on the Government to hold the early general election the country needs."

The letter was organised by the Love Socialism Hate Brexit campaign and signatories include shadow treasury ministers Clive Lewis and Anneliese Dodds, shadow minister for disabled people Marsha de Cordova and shadow science minister Chi Onwurah.

Labour is deeply split over the issue of a second referendum, with a letter signed by 25 MPs on Thursday arguing against another public vote.

They warned it would "divide the country further and add uncertainty for business" and could be "exploited by the far-right, damage the trust of many core Labour voters and reduce our chances of winning a general election".

Meanwhile, May has been warned that a lengthy delay to Brexit could destroy the Conservative Party, with a minister claiming it would be a Tory "suicide note" if the UK had to fight the European elections.

The stark warning about the "seismic" changes to British politics that would be unleashed if the May 23 European Parliament elections went ahead came as the Government sought to revive talks with Labour aimed at finding a Brexit compromise.

Education Minister Nadhim Zahawi said the situation needed to be resolved quickly in order to avoid the "existential threat" posed if the UK remained in the EU at the time of the elections next month.

"It would be, I think, a suicide note of the Conservative Party if we had to fight the European elections," he said.

He said that if Labour could not sign up to a joint approach, then MPs should be forced to find a compromise through a preferential voting system in order to resolve the situation.

"We need to do that quickly because, I think, going into the EU elections for the Conservative Party, or indeed for the Labour Party, and telling our constituents why we haven't been able to deliver Brexit, I think would be an existential threat," he told BBC Radio 4's Today programme.

It another development, Ireland’s premier warned that any EU country that vetoed a further Brexit extension would not be forgiven by other member states.

Taoiseach Leo Varadkar said he believed the prospect of one of the EU27 saying no to another extension at next week's European Council meeting was "extremely unlikely".

He suggested his own preference was for a longer extension than the June 30 date proposed by the UK.