A UK Government move to suspend parts of the Northern Ireland Protocol could endanger the entire Brexit withdrawal deal, Sinn Fein’s president has said.

Mary Lou McDonald was referencing the potential for the EU to take retaliatory action if the UK follows through with its threat to trigger the suspension mechanism – Article 16 – in the post-Brexit arrangements for Irish Sea trade.

On the prospect of the UK activating Article 16, McDonald said: “It would demonstrate just again colossal bad faith and demonstrate again that Ireland, the north of Ireland in particular, is collateral damage in the Tory Brexit as they play games and play a game of chicken with the European institutions.

“I would also say that if the British government imagine that they hold all of the cards they are wrong and they’re playing a very, very dangerous game, up to and including perhaps jeopardising the entire withdrawal agreement.”

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McDonald said the EU proposals for addressing issues with the protocol had gone further than many had anticipated.

“But, you know, everything has its elastic limit,” she told BBC One NI’s Sunday Politics programme.

“The reality now is the ball is at the foot of Boris Johnson and his Government, and they need to act in good faith and they need to adopt a position that is serious and that has a long-term view.

“If they don’t, well, then the consequences, I think, will be very grave indeed.”

The Sinn Fein leader’s comments came as negotiations between London and Brussels over the protocol remain deadlocked and amid mounting speculation that the UK Government is poised to trigger Article 16 later this month.

The oversight role of the European Court of Justice in policing the operation of the protocol remains a key sticking point in the talks to resolve issues with its operation.

The protocol’s purpose was to avoid the creation of a hard border on the island of Ireland, and in effect keeps Northern Ireland within the EU’s single market for goods.