The idea of excluding party leaders from meetings over the Northern Ireland Protocol needs to be “knocked on the head now”, Sinn Fein leader Mary Lou McDonald has insisted.

She was speaking after Northern Ireland Secretary Chris Heaton-Harris defended a decision not to invite her this week to roundtable talks with Foreign Secretary James Cleverly, which also discussed the Stormont powersharing crisis.

Mr Heaton-Harris said it may not have been wise to have the Sinn Fein president, who is the leader of the opposition in the Republic, because she is a “representative of a parliament in an EU member state”.

The UK Government and EU are involved in negotiations to resolve differences over the protocol.

The row led to Sinn Fein and the SDLP refusing to attend the meeting on Wednesday and has overshadowed a series of talks to discuss how to resolve issues caused by the post-Brexit trading arrangement.

The Government has also suggested that, due to diplomatic protocol, Mr Cleverly could not meet Mrs McDonald before he had met his counterpart in Ireland, Micheal Martin.

But Mr Martin said he would have had no issue with the Sinn Fein leader attending the meeting.

The row led DUP leader Sir Jeffrey Donaldson to query who leads Sinn Fein in Northern Ireland.

He said: “If in the future Mary Lou McDonald became taoiseach and we had Michelle O’Neill as first minister, who’s the boss? Who’s in charge?

“If we have meetings on a north-south basis, who’s in charge? And I think these are issues that Sinn Fein need to work out.

“I don’t need to have a minder with me every time I go to a meeting as the leader of the DUP, so who leads Sinn Fein in Northern Ireland, is it Mary Lou McDonald or is it not?”

Speaking on Thursday, Mrs McDonald said: “All of us know that the way that we make progress is together, that’s how this works, that’s what the history of the last 25 years reflects, so any idea of excluding anybody, excluding the leader of any party, needs to be scotched and knocked on the head now.”

She also confirmed she had written to Prime Minister Rishi Sunak about the issue.

Brexit
Northern Ireland Secretary Chris Heaton-Harris has suggested it might not have been wise to invite the Sinn Fein leader to a meeting to discuss the NI Protocol (Brian Lawless/PA)

Responding to the controversy, Mr Heaton-Harris said: “Sinn Fein were invited, it is a shame (Sinn Fein vice president) Michelle (O’Neill) didn’t come along because it was an update on the protocol discussions.

“There are many factors which go into the thought process. One, to be quite frank, is that the UK Government is negotiating with the European Union.

“We wanted to update Northern Ireland parties on that negotiation and, with the greatest of respect, Mary Lou is a representative of a parliament in an EU member state.

“That might not have been seen as a wise thing to do.”

Mr Heaton-Harris said he had extended an invite to dinner to Mrs McDonald.

“What happened yesterday, happened yesterday. I’m much more focused on the big ticket items.”

Responding to the dinner invitation, Ms O’Neill said: “We’re not interested in dinner.”

Brexit
Tanaiste and Minister for Foreign Affairs Micheal Martin said he did not know in advance about the decision not to invite Mary Lou McDonald to a political leaders’ meeting (Brian Lawless/PA)

Speaking about the row following a meeting with the Northern Ireland Secretary, Mr Martin said: “We certainly got no heads-up in relation to that at all, and I think it needs to be stated.

“I would have had no difficulty that Mary Lou McDonald was at that meeting but that’s a matter for the Foreign Secretary.”

Alliance Party deputy leader, Stephen Farry, was asked about Mr Heaton-Harris’s contention that it would have been unwise to invite Mrs McDonald to Wednesday’s meeting.

Brexit
Alliance Party MP Stephen Farry said the Government had made a mistake (Brian Lawless/PA)

“I think he needs to back down from that,” he said.

“The Government made a mistake in terms of how they handled the talks yesterday, their position on that is not tenable.

“They need to recognise the subtleties of the situation in Northern Ireland and the reality that Sinn Fein is organised on an all-Ireland basis.

“The Government need to de-escalate their language and they need to climb down and find a means of ensuring that we have proper inclusive talks at the next opportunity.”

Brexit
UUP leader Doug Beattie said he hoped all parties would attend future talks (Brian Lawless/PA)

Ulster Unionist leader Doug Beattie said he hoped that all political parties from Northern Ireland would take part in future talks with the Government.

“I wanted Sinn Fein to be there and I wanted the SDLP to be there.

“I wanted to hear what they had to say. I wanted us all to work together.

“And I’ve said this before, boycotts do not work of any shape or form. So whether it’s the DUP boycotting the executive or any other party boycotting talks, it simply won’t work.”

Ulster powersharing
Colum Eastwood, leader of the SDLP, said the British Government had created an ‘absolute mess’ (Liam McBurney/PA)

SDLP leader Colum Eastwood accused the British Government of being responsible for an “absolute mess”.

He said “When you are in a hole, stop digging, that is my advice to the Secretary of State.”