Tony Blair today warns that a vote for Britain to leave the EU will put “at risk” the future of Northern Ireland.

He will return to the scene of one of his biggest successes as prime minister to appeal to voters to reject Brexit and avoid “undermining” the United Kingdom. Blair, who brokered the Good Friday Agreement in 1998, will be campaigning alongside fellow former prime minister Sir John Major, who played a key role in re-starting the peace process during his time in the mid-1990s.

Blair will warn that stability in Northern Ireland would be put at risk because of the “ideological fixation” of campaigners seeking an exit from the EU referendum.

“I say, don’t take a punt on these people. Don’t let them take risks with Northern Ireland’s future. Don’t let them undermine our United Kingdom,” he is expected to say.

“We understand that, although today Northern Ireland is more stable and more prosperous than ever, that stability is poised on carefully constructed foundations.

“And so we are naturally concerned at the prospect of anything that could put those foundations at risk,” he will say, according to the Belfast Telegraph.

The rare joint intervention with Major, who Blair heavily beat in the 1997 election, prompted an angry response from Theresa Villiers, the Northern Ireland Secretary, who is supporting the Leave campaign. She said there would be no return to the Troubles, regardless of the result of the referendum, and that it was “irresponsible” to suggest otherwise.

Blair spoke out just 24 hours after he surprised many with a blunt attack on Jeremy Corbyn. He told Bloomberg the Labour leader came from the “politics of protest” and characterised him as “the guy with the placard”. However a spokesman for Corbyn said he was “leading the Opposition and building support against the Tory Government”.