O’Neill said in a statement she had been blocked from attending The Economic Forum in Glasgow on Friday, at which she would have met with her Scottish and Welsh counterparts John Swinney and Rhun ap Iorwerth, as well as Prime Minister Andy Burnham.

It is understood those leaders had been due to take part in a side meeting at the Glasgow event, and that O’Neill and Little-Pengelly were set to meet Burnham to discuss the Stormont budget.

However, posting on the social media platform Twitter/X, O’Neill claimed the block was a “reactive stunt, driven by the DUP’s own internal pressures and electoral problems”.

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O’Neill added on Twitter/X: “The deputy First Minister has decided to block representation from here at a major political event, which would include meeting with the First Ministers of Scotland and Wales, and the British Prime Minister.

She continued: “This is a reactive stunt, driven by the SUP’s own internal pressures and electoral problems. The DUP are unable to embrace equality, respect Irish identity, and accept a nationalist and republican now hold the office of First Minister.

“The days of domination are over. The days of treating people as second-class citizens are over. It is for the people to decide who represents them as First Minister. Not the DUP.

“I have contacted the British Secretary of State and made my position absolutely clear”.

(Image: John McVitty)

DUP leader Gavin Robinson later announced Little-Pengelly has ceased participating in joint engagements with O’Neill, and the party will not be giving permission for O’Neill to fulfil engagements on her own in the role of first minister.

It comes as members of the DUP’s main decision-making body will meet later to consider the party’s next steps amid the ongoing political fallout from the Drumcree parading dispute.

Upper Bann MP Carla Lockhart has been the most vocal voice within the DUP calling on the leadership to withdraw Little-Pengelly from the Stormont Executive – a move that would automatically force O’Neill from her post due to the joint nature of the powersharing structures in Northern Ireland.

Such a step would effectively collapse the devolved administration in Belfast as the Executive could no longer meet to make significant decisions.

Individual departmental ministers would, however, remain in post for up to six months and the Northern Ireland Assembly could continue to sit.

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Robinson has so far resisted pressure to pull Little-Pengelly out, arguing that imploding the Executive would damage unionism.

Lockhart resigned as a party officer last week over the difference of opinion with the leadership.

Others within the party have suggested action short of withdrawing the deputy First Minister, such as ending Little-Pengelly’s participation in further joint engagements with O’Neill.

Alliance MLA Paula Bradshaw, who is also the party’s chief whip, reacted to the statement: “This is deeply concerning. Five months out from the dissolution of the Assembly and we should be seeing collaboration between our FM and dFM to ensure that our govt depts are all pulling in the same direction for the people of NI: not this type of stunt politics.”