The European Union is expected to meet again on Monday to decide on a “specialised” framework to deal with the latest flare-up over the border between Northern Ireland and the Republic.
The issue has been one of the key sticking points in negotiations since Brexit.
There have been claims from both sides that Northern Ireland is being unfairly penalised by the UK, while the Republic insists the UK has not been properly consulted about the border.
The UK has rejected those claims and insisted that any agreement on the border must be “in the interests of the United Kingdom”.
The issue is a significant stumbling block for any deal.
The Brexit Secretary David Davis said on Sunday that the UK was ready to agree on a solution but only if the EU offered assurances on Northern Ireland.
The European Commission has rejected any suggestion that it is not being consulted on the issue.
The Irish government said the talks were continuing and there was “no point in talking”.
It accused the UK of trying to block progress on the Irish border, which it sees as a “key issue” for future peace.
The Government also faces another row over its decision to leave the EU, which has resulted in a raft of fresh issues in Northern Ireland, including the border, the economy and the way Northern Ireland votes.
The UK said on Friday it would not accept the tweet as a threat. “
This must end.”
The UK said on Friday it would not accept the tweet as a threat.
On Sunday, the British prime minister Theresa May told the BBC the UK’s withdrawal from the EU was a matter for “the UK”.
However, it was clear the issue of the border remained a sticking point.
“We’re going to have a good talk, I can assure you, but I think that the United States is going to come up with a solution,” Ms May said.
“There will be a very good and detailed discussion about how that is going and how we are going to make it work, because this is the most important issue that we’ve got to have, because the UK is not a member of the EU.”