Plans by the British Government to scrap aspects of the Northern Ireland Protocol could have a “colossal political and economic impact”, Sinn Fein vice president Michelle O’Neill has said.

During a party meeting in Belfast, Ms O’Neill launched an attack on Prime Minister Boris Johnson, who she said was motivated solely by holding on to power.

It was the first party meeting for Sinn Fein since it secured a historic victory in last month’s Assembly elections, emerging as the largest party in Northern Ireland for the first time.

However, the DUP has blocked attempts to restore the powersharing Stormont assembly or to form an executive as part of its protest against the protocol, which has created a trade border in the Irish Sea.

The UK Government has since revealed plans to introduce domestic legislation that would override parts of the Brexit deal for Northern Ireland.

Speaking about Mr Johnson, Ms O’Neill said: “Our interests are certainly not his interests, or that of the Tories.

“By ‘our interests’ I mean all of the people here, our local political democracy, our peace process, our progress and the transformation of the island over the past quarter of a century.

“They’ve no concern for our future – our shared future.

“Boris Johnson’s sole interests are holding on to power, and serving the sectional interests of a London elite.”

She added: “The DUP have saddled up to the Tories before, and of course they will never learn.

“What’s at play is that Boris Johnson wants to clutch on to power for as long as he can get away with it.

“The DUP and a faction of the Tories with whom they’re aligned want to squeeze from him what they can, while they can, on the Brexit protocol – a protocol which is necessary and a direct result of the hard Brexit the DUP and Tories championed.”

Ms O’Neill said: “Boris Johnson knows that to gamble the protocol is to breach international law and to jeopardise the British Government’s agreement with the EU on their withdrawal and future trading relationship with colossal political and economic impact.

“The threat of unilateral action by the Tories to legislate and breach international law serves nobody’s interests, anywhere at any time.

“With 40% of his own MPs diverging in this week’s confidence vote he has big choices to make in the interests of his own country and people.

“But, the absurdity of people of this island being subjected to this figure of disrepute is untenable.

“He is driving an anti-Good Friday Agreement agenda, which is disingenuously wrapped up in a pro-agreement rhetoric.

“Boris Johnson and (Northern Ireland Secretary) Brandon Lewis are giving the DUP cover and let’s be clear – the political stability of the north cannot be a hostage to the Tory in-fighting, Westminster chaos and continued DUP disruption.“

Ms O’Neill also said that if powersharing could not be restored in Northern Ireland, then there should be joint authority rule from Dublin and London.

She said: “If those elected to serve fail to restore the democratic institutions then it is not a case of direct rule from London on the cards, but joint authority from Dublin and London.

“And if the people decide, Sinn Fein hopes to lead that government from Dublin.”