The Irish prime minister has warned that soldiers may return to the border if Brexit goes “very wrong”.
Leo Varadkar said that in a worst-case scenario there could be a return of armed customs posts after the UK leaves the EU.
Mr Varadkar told Bloomberg TV the border at present was “totally open” but that if things went “very wrong” it would “look like 20 years ago”.
Asked to describe what a hard border would look like if the outcome of Brexit was a worst-case, Mr Varadkar said: “It would involve customs posts, it would involve people in uniform and it may involve the need, for example, for cameras, physical infrastructure, possibly a police presence or army presence to back it up.”
Labour leader Jeremy Corbyn told ITV News that "nobody wants there to be a hard border between Northern Ireland and the Republic of Ireland."
"I think the Good Friday Agreement was one of the historic achievements in political settlements to bring about some degree of peace, and that has to maintain."
"I don’t want troops there – because troops there would be a complete failure of the Good Friday Agreement and of the whole agreement about the European Union", he added.
Mr Varadkar's comments have been criticised by Democratic Unionist Party MP Gregory Campbell who said the Taoiseach should “dial down the rhetoric”.
“This is deeply unhelpful talk. Mr Varadkar knows full well the connotations of such statements and he knows it’s nonsense,” he added.
An Irish government spokesman issued a statement after the interview to clarify that Mr Varadkar was not referring to the Irish Army.
“The Taoiseach made it clear in the interview that the Government is determined to avoid a no-deal scenario and the consequent risk of a hard border,” the spokesman said.
“He was asked to describe a hard border, and gave a description of what it used to look like, and the risk of what it could look like in the worst-case scenario.
“He was not referring to Irish personnel and the Irish Government has no plans to deploy infrastructure or personnel at the border.”
Mr Varadkar also said Ireland is being victimised in the Brexit process and the government would not be giving up on the backstop mechanism for promises that the border issue would be rectified at a later date.
It comes as the clock ticks down to the March 29 deadline for the withdrawal of the UK from the EU.
With a deal yet to be agreed, the Chancellor of the Exchequer Philip Hammond has been on a mission at the World Economic Forum urging business leaders to trust the government to do what makes economic sense.
This is despite Mr Hammond not ruling out a no-deal Brexit.
In a speech on Thursday at the Belvedere Hotel, he told business leaders not leaving the EU “would be a betrayal of the referendum” but so too would leaving without a deal because it would “undermine Britain’s future prosperity”.
The only way to avoid no deal, Mr Hammond said, is for parliament to agree to the prime minister’s deal. The only credible way forward is a “negotiated settlement” with the EU.
“We have to find a way around the impasse around the Irish backstop”.