There will be no deal if the latest Brexit plan put forward by the UK is the “final proposal”, Irish deputy prime minister Simon Coveney has said.
The UK’s offer to the EU would replace the Irish border backstop through a number of different arrangements.
The Irish government is concerned about customs checks and a review mechanism for the devolved NI government.
DUP leader Arlene Foster described Mr Coveney’s remarks as “deeply unhelpful” and “obstructionist”.
Speaking on Thursday, Mrs Foster said she believed the Irish government was not interested in an alternative to the backstop.
The Irish deputy prime minister said giving Stormont a say on a single market deal coming into force could not be approved.
UK Prime Minister Boris Johnson’s plan would see Northern Ireland stay in the European single market for goods but leave the customs union – resulting in new customs checks.
Although the proposals were welcomed by the DUP, other political parties in Northern Ireland and business groups have dismissed it.
Stormont’s power-sharing government is currently not sitting – it collapsed two-and-a-half years ago amid a bitter row about a green energy scheme.