Northern Ireland must not be caught in the middle of a game of chicken between London and Brussels over post-Brexit trading arrangements, Michelle O’Neill has warned.

The Sinn Fein vice president said the Stormont institutions were at risk due to an “ideological war” between the UK Government and EU.

Ms O’Neill is entitled to the role of first minister in Northern Ireland after Sinn Fein emerged as the largest party in the recent Assembly election.

However, she has been denied that position due to a DUP boycott of the powersharing institutions in Belfast in protest at the Northern Ireland Protocol deal on Irish Sea trade.

The region’s largest unionist party insists the Irish Sea border, which requires checks on goods arriving in Northern Ireland from Great Britain, has undermined the basis for powersharing in the region and must be removed.

The DUP said until the Government acts on the protocol it will not fill the post of deputy first minister, a move required to form an executive, or agree to the nomination of an Assembly speaker to enable the devolved legislature to meet.

Ms O’Neill was commenting as the Government signalled an intent to act unilaterally to override aspects of protocol by way of domestic legislation at Westminster.

She said issues with the protocol could only be resolved through good faith negotiations between the UK and EU, not unilateral action by Boris Johnson.

“The behaviour of the British government and Boris Johnson in terms of initiating again legislation to override an international agreement does not bode well for a good faith negotiation and I think that puts us in jeopardy in terms of the uncertainty and instability that it provides for us here,” Ms O’Neill told BBC Radio Ulster.

“It’s a game of chicken that were caught up in the middle of.”

Ms O’Neill branded the DUP stance as “shameful”.

“It’s intolerable that they’re sitting outside the executive at a time when we have a cost-of-living crisis,” she said.

“It is absolutely shameful on their part.

“Here we are 11 days after the election when the people voted, they voted in large numbers for politics to work, they voted for parties to work together.

“We’re listening over the course of 24 hours to a situation around families struggling to provide food for their children over the summer months and what we have is no executive in place and that’s all because the DUP are stomping their feet about a Brexit which they helped deliver, the hardest possible Brexit which they helped deliver.”

Ms O’Neill said the already established joint UK/EU committee on the implementation of the protocol should be the route to resolve problems with the arrangements.

“Even at this late stage, I would say to the DUP join the rest of us in the executive, find ways to support the public right now who need us through this cost of living crisis and find other ways, through the joint committee for example, to find ways to smooth the implementation of the protocol because it is here to stay that was stated clearly yesterday (during Mr Johnson’s visit to Northern Ireland).

“An executive and the public should not be held to ransom for what’s happening between an ideological war between the Tories and the European Commission and also Brandon Lewis (Northern Ireland Secretary) and Boris Johnson pandering to the DUP and their nonsense right now whenever the public needs us to work for them.”