Britain's Brexit chief has accused the EU of not listening to his demands on Northern Ireland in a heated series of late-night posts on Twitter.
Lord Frost's comments came after Ireland's foreign minister Simon Coveney accused him of laying out red lines he knew the EU could not accept, to deliberately engineer a breakdown in relations.
The UK's Brexit minister said he preferred "not to do negotiations by twitter" but would proceed since Mr Coveney had "begun the process".
The Brexit minister wants to change the part of the deal relating to Northern Ireland but the EU says the UK must stand by what it has signed.
But Lord Frost specifically wants to dump jurisdiction of the European Court of Justice over the Northern Ireland deal, which he signed up to during talks but now is having second thoughts about.
Lord Frost claimed the UK's concerns around the court were not new as the UK had raised them in July. But he added: "The problem is that too few people seem to have listened."
Mr Coveney, who leads for Ireland on Brexit, had said the EU was "working seriously to resolve practical issues with implementation of Protocol" but accused the UK government of creating "a new 'red line' barrier to progress, that they know EU can’t move on"
He added: "…are we surprised?" And said the "real question was whether the UK government actually wanted "an agreed way forward or a further breakdown in relations".
The Irish foreign minister's comments echos concerns in Brussels where some officials believe Lord Frost simply want to twitter a meltdown of the Northern Ireland agreement, which the UK has never fully implemented.
The UK minister is due to fly to Lisbon on Tuesday to give a speech where he will repeat his threat to suspend the Brexit deal.
The UK says if the EU does not significantly change the deal then it will trigger Article 16 and suspend it unilaterally. Brussels is expected to issue its formal response to the UK this week.
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