Boris Johnson has suffered a blow to his proposed Brexit deal as the Democratic Unionist Party said it cannot support plans “as things stand”.
The support of the DUP is seen as crucial if the prime minister is to win Parliament’s approval for the deal in time for his 31 October deadline.
The DUP said it would continue to work with the government to try to get a “sensible” deal.
It comes as Mr Johnson heads to a crunch summit to get the EU’s approval.
On the EU’s side, the legal text of a draft Brexit deal is seen as being “pretty much ready”, the BBC’s Europe editor Katya Adler said.
But the UK government has yet to approve the documents and the DUP remains unhappy about elements of the prime minister’s revised plan for Northern Ireland.
In a joint statement released on Thursday, the DUP’s leader and deputy said discussions with the government were “ongoing” but “as things stand, we could not support what is being suggested on customs and consent issues and there is a lack of clarity on VAT”.
“We will continue to work with the government to try and get a sensible deal that works for Northern Ireland and protects the economic and constitutional integrity of the United Kingdom,” Arlene Foster and Nigel Dodds added.