The Irish government has warned UK authorities it will not be used as a "pawn" in Brexit negotiations.
Foreign Affairs Minister Simon Coveney said he does not want the issue of the Irish border to be used by the UK government as a tool to pressurise the EU for broader trade agreements.
Mr Coveney also said that sufficient progress on the future of the Irish border has not been made during Brexit talks.
Speaking ahead of a meeting with Northern Ireland Secretary of State James Brokenshire in Dublin on Tuesday Mr Coveney said: "We do not want the Irish issue, the border issue, to be used as a pawn to try to pressurise for broader trade agreements."
He added: "Sufficient progress (on the issues facing the island of Ireland post-Brexit) hasn't been made to date."
He warned that in order for Brexit negotiations to move onto the next phase "measurable and real progress" is needed.
Before the meeting Mr Brokenshire insisted there was no possibility of the UK staying within a customs union post Brexit.
He said that to do so would prevent the UK from negotiating international trade deals.
However, following a meeting with the Irish and British Chamber of Commerce he said there would be a period of implementation where the UK would adhere closely to the existing customs union.
"We think it is important there is an implementation period where the UK would adhere closely to the existing customs union," said Mr Brokenshire.
"But ultimately it is about the UK being able to negotiate international trade deals. We want to harness those freedoms. If we were to remain in the customs union that would prevent us from doing so.
"We are leaving EU, customs union and single market. We have set out options as to how we can achieve that friction less trade," he added.
However, Mr Coveney said the Irish Government believes the best way to progress "the complexity of Britain leaving the European Union is for Britain to remain very close to the single market and effectively to remain part of the customs union."
He added: "That would certainly make the issues on the island of Ireland an awful lot easier to manage.
"But of course the British Government's stated position is not in agreement with that but that doesn't mean we won't continue to advocate for that.
"In the absence of that it is up to the British government to come up with flexible and imaginative solutions to actually try to deal with the specific island of Ireland issues."