The Taoiseach said critics who warned the controversial trading arrangements were tearing the union apart were being “over-dramatic”. Mr Martin spoke out after Boris Johnson vowed to take action on the Northern Ireland Protocol if the EU refuses to ditch “absurd” aspects of the post-Brexit customs system.
He told BBC NI’s Spotlight programme: “The Protocol is not tearing the United Kingdom apart, that’s just an overly dramatic presentation of it in our view.
“It explicitly affirms the constitutional position of Northern Ireland and the principle of consent.
“So it’s not a danger to the constitutional position of Northern Ireland at all, and was never intended to be.”
His comments came in response to Mr Johnson’s claims that the Government was currently working on “sandpapering” the Protocol, which governs Irish Sea trade post-Brexit, to address some of the concerns about trade disruption.
The Protocol formed part of the Brexit withdrawal agreement which was signed on Christmas Eve and cleared the way for Britain’s departure from the EU a week later.
But it has led to soaring tensions in Northern Ireland and remains a major bone of contention between London and Brussels.
READ MORE Brexit LIVE: Where are the doom-mongers now?
Also speaking on BBC NI’s Spotlight programme, the Prime Minister was questioned on the potential of a future poll on Northern Ireland’s constitutional status.
Mr Johnson said he could not envisage such a vote for “a very, very long time to come”.
The unpopular trading arrangements have been cited as a factor behind the recent upsurge of violence in loyalist areas in Northern Ireland.
Loyalists believe the new economic barriers between the region and Great Britain have weakened their place in the UK.
The EU has taken legal action against the UK for its decision to unilaterally extend some of those grace periods amid continuing talks between the two sides on ways to ease the red tape burden.
Mr Johnson has hinted he will trigger a mechanism to suspend the Protocol – Article 16 – if changes to the arrangements cannot be agreed upon.
He said: “If we can’t make enough progress and if it looks as though the EU is going to be very, very dogmatic about it and we continue to have absurd situations so you can’t bring in rose bushes with British soil into Northern Ireland, you can’t bring British sausages into Northern Ireland, then frankly I’m going to, we’ll have to take further steps.
“What we’re doing is removing what I think of as the unnecessary protuberances and barriers that have grown up and we’re getting the barnacles off the thing and sandpapering it into shape.”