JEREMY CORBYN revealed documents exposing Boris Johnson’s “falsehoods” over his Brexit deal today — including his assurances that there would be no customs border in the Irish Sea.

The Labour leader accused Mr Johnson of “deliberately misleading the country” over his Brexit deal.

During a press conference in the central London office of public-sector union Unison, the Labour leader held up 15 pages of secret documents from the Treasury.

Mr Corbyn said, while holding copies of a set of confidential presentation slides titled Northern Ireland Protocol — Unfettered Access To The UK Internal Market: “This is cold, hard evidence that categorically shows the impact a damaging Brexit deal would have on large parts of our country.”

He said they show that Mr Johnson’s plans for leaving the EU would result in post-Brexit customs checks and “potentially damaging tariffs” — effectively a “hard border.”

The confidential government report “drives a coach and horses” through the Prime Minister’s claim that there will be no border in the Irish Sea under his plan, he added.

Page five of the document, seen by the Star, states: “There will be customs declarations and security checks between Northern Ireland and Great Britain.”

Labour says that Mr Johnson’s deal means that he has to choose between two likely scenarios.

The choice would be between protecting the UK Internal Market (UKIM) and inflicting “significant economic damage on Northern Ireland, risking the peace process” or allowing “unfettered access” for trade that would “breach international law and risk the UKIM being flooded with unregulated goods, which would put at risk the ability to agree trade deals with other countries.”

Mr Johnson dismissed Labour claims as “complete nonsense” even though he admitted that he had not seen the documents himself.

He later added: “[People] should believe exactly what I say, which is that there will be no goods going from GB to NI or from NI to GB [sic] because we are going to come out of the EU whole and entire, and that was the objective that we secured.”

The Conservatives said the document presented by Mr Corbyn was only an immediate assessment of the PM’s deal and represents an incomplete analysis.

Unison general secretary Dave Prentis said: “Once again, government documents show you can’t trust Boris Johnson.

“His reckless approach and cavalier disregard for the truth is putting at risk the hard-won peace in Northern Ireland.

“It’s vital the Good Friday Agreement is protected by the next government.”

The reveal of the documents came as former Tory PM John Major endorsed three ex-Tory independent candidates running against Mr Johnson’s party in next week’s election — effectively suggesting a tactical vote against the Conservative Party.

He said he would vote for David Gauke, Dominic Grieve and Anne Milton — who all lost the party whip after voting for an amendment ruling out a no-deal Brexit — if he lived in their constituencies.

Responding to Mr Major, the PM said: “I think that he is wrong, and I think that he represents a view that is outdated.”

The reveal of the documents also came before Mr Johnson and Mr Corbyn went head to head in a BBC leadership debate last night.