Ulster Unionist Party leader Doug Beattie has claimed he fears potential violence in Northern Ireland this summer if there is no progress on the protocol in the coming weeks.
Speaking in front of a House of Lords sub-committee on the post-Brexit trading arrangements, Mr Beattie said frustrations in the province “could come to the boil” and claimed it “doesn’t take much to go from a stone to a petrol bomb and from a petrol bomb to a bullet”.
"If you look at last year and look at the summer of last year, we had Covid and had the command paper of July. Maybe in many cases that kept much of the frustrations down,” he said.
"My big fear is if there is nothing this summer, those frustrations could come to the boil if people are not moving and trying to fix the problems we have in Northern Ireland.
"It doesn’t take much to go from a brick to a stone and from a stone to a petrol bomb and to a petrol bomb to a bullet and from a bullet to a coffin.”
Legislation around the Northern Ireland Protocol was initially expected to be tabled on Thursday, however reports have since emerged the legislation has been delayed until next week.
The DUP is refusing to enter the powersharing institutions until issues with the post-Brexit settlement for Northern Ireland are addressed.
It comes as Labour leader Sir Keir Starmer will visit Belfast as part of a meeting over the protocol.
Sir Keir will arrive in Dublin on Wednesday evening for a dinner with the British-Irish Chamber, before meeting President Michael D Higgins and Taoiseach Micheal Martin.
He will also visit Belfast as part of the trip and meet with Irish Foreign Affairs Minister Simon Coveney, before speaking with political leaders in Stormont.
Speaking during his witness session in Westminster, leader Sir Jeffrey Donaldson accused the Irish Government of being tone deaf and ignoring unionists concerns about the impact of the protocol.
Mr Donaldson said the protocol has left him being treated like a second class citizen in Northern Ireland.
He told the Lords sub-committee on the Northern Ireland Protocol that Irish ministers give "vague" answers to his concerns about the purpose of the protocol.
"There are some who argue that main purpose is to re-orientate the Northern Ireland economy away from Great Britain's economy and develop an all-island economy, an economy that does not exist, and that you would bind the Northern Ireland economy more closely to the economy of the Republic," Sir Jeffrey added.
"I've asked Irish Government ministers about this and they give vague answers.
"There is a difference between cross-border trade and all island economy."
Sir Jeffrey also said he found comments made by Taoiseach Micheal Martin earlier on Wednesday to be "deeply disappointing".
Mr Martin said the UK Government's proposed legislation to deal with the protocol would be "to the benefit of absolutely no-one".
The Irish leader accused London of failing to engage with the EU to reach a negotiated settlement on changing aspects of the protocol's operation.
"I listened to the comments from Micheal Martin and I found them deeply disappointing.
"They are tone deaf to concerns to unionists.
"They don't get it and if they do they ignore it," Sir Jeffrey added.
According to reports, Prime Minister Boris Johnson will bring forward a Bill which could allow him to potentially scrap elements of the contentious post-Brexit trading arrangements.
Earlier, Mr Johnson faced claims the Government has failed to consult one of its senior legal advisers over the plans.
Boris Johnson rejected the claim that First Treasury Counsel Sir James Eadie, the Government's independent barrister on major legal issues, had not been asked to give a view on the contentious Bill due to be tabled at Westminster.
The UK Government intends to use domestic law to override aspects of the post-Brexit arrangements governing Irish Sea trade, which were jointly agreed by the UK and EU as part of the Withdrawal Agreement.
SDLP leader and Foyle MP Colum Eastwood challenged Mr Johnson on the report during Prime Minister's Questions in the Commons.
"I can tell him that the reports that he has seen this morning are not correct," replied Mr Johnson.
"And what I can also tell him is that the most important commitment that I think everybody in this House has made is to the balance and symmetry of the Belfast/Good Friday Agreement.
"That is our highest legal international priority and that is what we must deliver."
The UK is moving without the consent of the EU to change the terms of the protocol to reduce the checks it requires on the movement of goods between Great Britain and Northern Ireland.
The dispute over the protocol has led to a political impasse at Stormont, with the DUP blocking the re-establishment of a devolved executive until major changes are secured to arrangements the party claims have weakened Northern Ireland's place within the United Kingdom.
Northern Ireland's 1998 Good Friday/Belfast peace agreement contains provisions to protect and develop relations both on a north/south basis on the island of Ireland and on an east/west basis between the island and Great Britain.
The DUP claims, and the Government agrees, that the protocol has upset this "delicate balance" of unionist and nationalist aspirations by undermining the east/west dynamic.