Leaving the European Union would endanger not just the ongoing peace process, but also the very existence of the UK, two former prime ministers have warned.
Former rivals Sir John Major and his successor Tony Blair yesterday joined forces in Londonderry as part of the campaign to keep the UK in the EU.
Both men played key roles in the peace process, but their dire warning that politics here would be put at risk by a Brexit was denounced by DUP MP Nigel Dodds, who described Mr Blair's words as "dangerous and destabilising".
The former Labour prime minister told students at Ulster University's Magee campus in Londonderry that Northern Ireland would feel the effect of Brexit more than any other region in the UK.
Mr Blair said: "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.
"When we negotiated the Good Friday Agreement, one vital part of it that people often overlooked was that it also (created) a new relationship between the Republic of Ireland and the UK within the European Union.
"Europe was also part of the complex foundations on which we were able make peace in Northern Ireland."
Former Conservative prime minister John Major predicted Scotland would seek independence in the event of a Brexit.
"If Scotland votes in the referendum to stay in the European Union but the UK as a whole chooses to leave, there is a serious risk of a new referendum," Mr Major said.
"Not straight away, perhaps, but, ultimately, nationalist pressure for another shot at Scotland leaving the UK could be uncontrollable and irresistible.
"In those circumstances, if the UK is outside the European Union, I can well envisage a different result, so that is the risk.
"A British exit from the European Union could reopen the whole issue of independence and could tear apart the United Kingdom - the United Kingdom, outside the European Union and Scotland outside the United Kingdom.
"The most successful union in world history would be broken apart."
But speaking in the House of Commons, a furious Mr Dodds called for a debate to "debunk the nonsense spoken by the former prime minister Tony Blair".
The Pro-Brexit DUP deputy leader also condemned the former Labour prime minister's comments as "irresponsible nonsense".
He added: "Surely this is the most irresponsible talk that can be perpetuated in terms of Northern Ireland - very dangerous, destabilising and it should not be happening."
Mr Dodds later told BBC Radio 4's World At One that the two former prime ministers were engaging in "scaremongering".
"I think it's deeply disappointing," he said. "They know that the peace process in Northern Ireland has never been more stable. They are devaluing their own legacy."
Meanwhile, former US president Bill Clinton, whose 1995 visit to Northern Ireland was seen as a crucial moment in the peace process, said he was worried about the potential impact of Brexit on the province.
Writing in the New Statesman magazine, Mr Clinton said: "I was honoured to support the peace process in Northern Ireland. It has benefited from the UK's membership in the European Union, and I worry that the future prosperity and peace of Northern Ireland could be jeopardised if Britain withdraws."
The former president, who worked with Sir John and Mr Blair on the peace process, added: "Transatlantic co-operation is essential, and that cooperation is strongest when Europe is united. I hope you will stay."