The Tanaiste has urged the British government to bring forward any viable alternatives to the backstop.
Simon Coveney met with the UK Foreign Secretary for 45 minutes in Helsinki today.
He told Dominic Rabb the Withdrawal Agreement is not up for renegotiation.
Mr Coveney, said so far the UK had not put forward any “credible” alternatives to the backstop – the contingency plan aimed at preventing a hard border with the UK.
“It can’t simply be this notion that ‘look, we must have the backstop removed and we will solve this problem in the future negotiation’ without any credible way of doing that,” he said.
“That’s not going to fly and it’s important that we are all honest about that.”
By Vivienne Clarke and PA
Tánaiste Simon Coveney has accused the British Prime Minister, Boris Johnson, of being "totally unreasonable" over Brexit backstop.
Mr Coveney said the UK has not made credible proposals to replace the backstop.
Speaking on Newstalk, the Foreign Affairs Minister said Mr Johnson's team had not offered any concrete alternatives to the backstop.
"Boris Johnson is outlining a very clear and firm position but it is a totally unreasonable position that the EU cannot facilitate and he must know that," Mr Coveney said.
"We all want to get a deal but, at the moment, nothing credible has come from the UK government in terms of alternatives to the backstop," he told reporters.
‘There’s no country that wants a deal more than Ireland. We want good relations with the UK in the future. We share a lot of responsibility in the island of Ireland, north and south, that Brexit is very disruptive towards.
"If there are alternatives to the backstop that do the same job, well then let's hear them. And if we can work out a deal on that basis, so be it, but it's got to be credible.
"It cannot simply be this notion that we must have the backstop removed and we'll solve this problem in the future negotiations, without any credible way of doing that. That's not going to fly."
On Boris Johnson’s suggestion of negotiations for two days a week, Mr Coveney said: “I’m sure if he wanted five days of negotiations a week, the EU would be okay with that.
“Michel Barnier is there as the chief negotiator for that purpose, he has a team that’s ready to go.
“We all want to get a deal but at the moment nothing credible has come from the British Government in the context of an alternative to the backstop.
“If that changes, great. We’ll look at it in Dublin but more importantly it can be the basis of a discussion in Brussels, but it’s got to be credible.
“It can’t simply be this notion that ‘look we must have the backstop removed and we’ll solve this problem in the future negotiation, without any credible way of doing that’. That’s not going to fly and I think it’s important that we are all honest about that.
“We have always said if there are alternatives to the backstop that do the same job, then let’s hear them and if we can work out a deal on that basis, so be it.
“But what we will not do in Ireland, and I believe there is strong solidarity across the EU on this, we will not allow a really important element of the Withdrawal Agreement to be removed – i.e. the backstop, which solves a difficult problem, albeit on a temporary basis – and for that to be replaced with something that doesn’t stand up to scrutiny and is simply a promise that we’ll do our best to solve the problem, but not explain how.
“That is not an approach that either Ireland or the EU will support.”
Additional reporting Press Association