The DUP will not be “brow beaten” into a return to powersharing in Northern Ireland, its party leader has warned.

Sir Jeffrey Donaldson’s comments came after Northern Ireland Secretary Chris Heaton-Harris claimed a restoration of the Stormont institutions was the surest way to secure the region’s place in the UK.

Addressing a major conference in Belfast commemorating the 25th anniversary of the Good Friday Agreement, Mr Heaton-Harris said “real leadership” was about having the courage to say “yes” as he hailed decisions made by previous unionist leaders during the peace process.

While Downing Street has denied the speech signalled a toughening up of the Government’s messaging towards the DUP, many have interpreted the remarks as a change in tone around the ongoing Stormont impasse.

Good Friday Agreement 25th Anniversary
Northern Ireland Secretary Chris Heaton-Harris addressing the conference at Queen’s University (Niall Carson/PA)

The DUP is currently blocking the functioning of the Stormont institutions in protest at post-Brexit trading arrangements the party contends have created economic barriers between Northern Ireland and the rest of the UK.

The Government insists the DUP concerns have been addressed by the new trading deal it struck with the EU, the Windsor Framework.

But Northern Ireland’s largest unionist party has insisted the Government needs to provide it with further legal assurances on sovereignty and the application of EU law in Northern Ireland.

“The great and the good can lecture us all they want for a cheap round of applause but it won’t change the political reality,” Sir Jeffrey tweeted on Tuesday.

“The political institutions only work when there is cross community consensus. Berating unionists won’t solve the problem. They didn’t do it to Sinn Fein (when the party collapsed powersharing in 2017) and we will not be treated differently or brow beaten into submission.

“The Government need to work with us to address concerns and get the outstanding issues resolved. We stand ready to get the job done and see Stormont restored. But it has to have a solid foundation.”

Good Friday Agreement 25th Anniversary
Sinn Fein vice president Michelle O’Neill speaking to the media at the Queen’s conference (Niall Carson/PA).

Earlier, the Northern Ireland Secretary said those who are proud of the region’s place in the Union “should put the Union first” and restore the devolved institutions.

Mr Heaton-Harris was speaking at the three-day conference at Queen’s University to mark the 25th anniversary of the Good Friday accord.

He said the narrative that unionism was not served well by the 1998 peace deal was “wrong”.

Speaking in the Whitla Hall at Queen’s, he said he has been struck by a narrative that has “become louder in recent years – a narrative that the Agreement struck in 1998 did not achieve great things for unionism”.

He said: “That it was somehow all-out wins for nationalism. That narrative is wrong. And all of those, all of us who support the Agreement, must be vocal in countering it.

“Today, the principle of consent is so often taken for granted but it was an important and hard-won guarantee that settled Northern Ireland to remain as part of the United Kingdom.”

Mr Heaton-Harris said the “simple reality” is that people tend to change the status quo only when the status quo is not working, or people simply stop making the case for it.

“Devolved powersharing institutions created a status quo that those of us who value Northern Ireland’s place in the Union can robustly and successfully promote and celebrate,” he said.

“So let no-one tell you that powersharing is at any way at odds with unionism.

“Instead it is the surest way by which Northern Ireland’s place in the Union can be secured,” he said, in comments that prompted applause from the crowd.

Mr Heaton-Harris added: “I make no apologies for being proud of Northern Ireland’s place in the Union and for wanting it to continue.

“Others who share that view should put the Union first, restore the devolved institutions and get on with the job of delivering for the people of Northern Ireland.”

Good Friday Agreement 25th Anniversary
Tanaiste Micheal Martin talking to the media in the grounds of Queen’s University (Niall Carson/PA)

Mr Heaton-Harris said real leadership is about having the courage to say “yes”, telling the crowd: “Like David Trimble (former UUP leader), David Ervine (former Progressive Unionist Party leader) before in 1998, Dr Paisley in 2006 (former DUP leader Ian Paisley), real leadership is about knowing when to say yes and having the courage to do so.”

Asked about the tone and content of Mr Heaton-Harris’s speech, the Prime Minister’s official spokesman said that ministers had used “similar” messaging before, amid efforts to restore powersharing.

“We think it is important that the people of Northern Ireland have an up and running, functioning executive,” he said.

“Our priority is ensuring that is delivered, it is something we have been working on before the framework and obviously we believe that the framework provides the right foundation for powersharing to return.”

Sir Jeffrey has not participated in the conference in its first two days. His party colleague Emma Little-Pengelly told the event on Tuesday that some messages emerging from the stage had “demeaned or dismissed” unionist concerns.

Sinn Fein’s Stormont leader, Michelle O’Neill, who is in line to become first minister if devolution is restored, said the theme of the conference had been one of “encouragement”.

“I don’t think it’s been deliberately antagonistic towards anybody,” she said.

“I think it’s been absolutely determined to be positive and to try to encourage the parties to come together.

“There isn’t any other show in town.”

Good Friday Agreement 25th Anniversary
Vice-president of the European Commission Maros Sefcovic attended the conference (Niall Carson/PA).

Earlier, Ireland’s deputy premier Micheal Martin also called for the return of the Stormont executive, saying the UK Government “stretched themselves” to achieve the Windsor Framework.

“The past few years, with the practicalities of Brexit, have been turbulent for Northern Ireland, and for these islands,” he said.

“The European Commission and the UK Government stretched themselves in recent months to reach an accommodation that works for Northern Ireland.

“I know that turbulence will take some time to settle, that parties need to pause and reflect internally on next steps.

“But I urge all elected officials to take their seats in the assembly and the executive and get to work on the questions of everyday life that matter to the people of Northern Ireland, including healthcare, education, policing, regional imbalances and much more.”

Mr Martin also called on the Northern Ireland parties to recapture the spirit of the Good Friday Agreement.

European Commission vice-president Maros Sefcovic, who also attended the conference on Tuesday, hailed the importance of “inclusivity”.

In a panel discussion focused on the Good Friday Agreement being a template for resolving global conflict, Mr Sefcovic said “lesson number one” is “respect your partner”.

He also said that the establishment of a strong personal relationship is important, adding that he was happy to have had a strong relationship within a very short period of time with both Foreign Secretary James Cleverly and Mr Heaton-Harris.

The event at the Queen’s University Belfast has seen the participation of major political figures including former US president Bill Clinton, former prime minister Sir Tony Blair and former taoiseach Bertie Ahern.

Prime Minister Rishi Sunak is scheduled to make a closing address to the conference on Wednesday ahead of a dinner event which former prime ministers Boris Johnson and Liz Truss are expected to attend.