BORIS Johnson has said customs checks will be necessary on the "island of Ireland" after Brexit but insisted they could be "minimal and non-intrusive".
The British prime minister's comments came after he disowned proposals for customs centres between five and 10 miles either side of the border, which had been reported by RTÉ.
With his government set to table fresh proposals to the EU aimed at breaking the border logjam, he said some checks may be necessary.
"If the EU is going to insist on customs checks as we come out as it is, then we will have to accept that reality – and there will have to be a system for customs checks away from the border," he told the BBC.
"Now, we think those checks can be absolutely minimal and non intrusive and won't involve new infrastructure."
He said the negotiations with the EU "will be tough."
Mr Johnson urged leaders in Brussels, Dublin and Berlin to work with him as the "rubber hits the road" on efforts to strike a deal ahead of the October 31 scheduled Brexit date.
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He said proposals for an all-Ireland zone for animal health measures would also "logically imply some more checks down the Irish Sea" but that such arrangements would be "liveable with, provided it's done in the right way".
But Tanáiste Simon Coveney said the Tory leader was trying to shift responsibility away from commitments to prevent a hard border that have been given in the past.
"This is something that we spent over two years discussing and negotiating and looking at multiple different ways of trying to solve," he told RTÉ.
"Where we landed at the end of that process was a compromise that was designed by the British side as well as the EU side, with a lot of Irish input, and it became known as the backstop."
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The Fine Gael deputy leader said the backstop was a default position for avoiding border infrastructure but that Mr Johnson wanted to remove the key element relating to Ireland.
"What we're saying is, if you want to do that, then the onus is on you to come up with a solution to the problems that that causes. And so far, we have not seen either a credible or a serious proposal that can achieve the same outcome as the backstop," he said.
Mr Coveney said that there are other ways in which we can look at accommodating change to what was previously agreed.
SDLP Brexit spokesman Daniel McCrossan said it was no surprise the British government wanted to harden the border.
"Despite Boris now backtracking on this leak, it’s clear this Tory government have no clue what they are doing," he said.
"They have been reckless and have been playing with peoples lives and livelihoods – it’s time the British government stopped giving in to the DUP and got back to the table with proposals that actually facilitate the status quo rather than policies of division."
European Commission spokeswoman Mina Andreeva said: "We have not received any proposals from the United Kingdom that meet all the objectives of the backstop, as we have been reiterating and demanding."
"It's the UK's responsibility to come forward with workable and legally operational solutions that meet all of the objectives of the backstop."
