Sinn Fein have branded the DUP "foolish" for backing Boris Johnson's plans to suspend Parliament ahead of a Queen's Speech.
The party's MLA Conor Murphy made the comments on Wednesday after it emerged that the Prime Minister intends to suspend Parliament from around September 11 until a new Queen's Speech on October 14.
Sinn Fein joined politicians from across the UK in criticising the move, saying it is part of a plan by the PM to stop MPs legislating against a no-deal Brexit.
Mr Johnson denied the claim as "completely untrue", saying the Queen's Speech would be an opportunity to outline his "very exciting agenda" for the future.
DUP leader Arlene Foster welcomed the move and said it would give her party the chance to review their Confidence and Supply Agreement with the Government.
Mr Murphy said that the DUP were "foolish to throw their weight behind the Tories".
"By throwing their weight behind the British government today, who are clearly determined to drive through a no-deal Brexit, once again they are demonstrating their own contempt for the people who elected all of us in this part of the world," the Newry and Armagh MLA said.
"They have had every opportunity to act in the interests of the people of the north of Ireland, who voted to remain, but they have continued to side with the British government.
“Today’s move by the British Prime Minister Boris Johnson proves that the interests of Ireland will never be served or defended by Westminster.”
Mr Murphy said calls for the party to take their seven Westminster seats in a bid to thwart a no-deal were "absurd".
He said Boris Johnson's move to suspend parliament showed how impotent the Westminster institutions are.
"This day of all days when the British government decided to set aside parliamentary interests, decided to ride roughshod over the parliament and force their own position, then the argument that Sinn Fein should be sitting in there, as impotent as the rest of the MPs, I think is a nonsense," he said.
Sinn Fein President Mary Lou McDonald said the move showed the "arrogance and contempt of the Tories" and said that it was clear the Mr Johnson intended to "force through" a no-deal Brexit regardless of the consequences for Northern Ireland or the Irish Republic.
"It shows the arrogance of the British government and their contempt even for their own political institutions and it is very clear that Irish interests will never be protected at Westminster," she said.
"The fact is that Brexit is incompatible with the Good Friday Agreement and the Tories have shown a total and callous disregard for our country and the democratically expressed wishes of the people of the north to remain in the EU. The need to protect Irish interests is paramount.
"Sinn Fein will continue to stand up for our interests against Tory Brexiteers and their catastrophic Brexit agenda, and we will continue to work with the EU and the Irish government to that end.”
Alliance Party leader Naomi Long accused the PM of acting like "a dictator".
“It is the desperate act of a Prime Minister who knows Parliament opposes a no deal but who will attempt to push it through regardless," the MEP said.
"He has no mandate for this and has ploughed on ahead, despite knowing the consequences of Brexit in general and no deal in particular. Efforts must continue to prevent that scenario."