Former British prime minister John Major has said "every effort" must be made to ensure the Northern Ireland Protocol dispute is solved.
The former Tory party leader said that the protocol was "one of the least well-done negotiations in modern history".
He gave evidence to the Oireachtas Good Friday Committee on Thursday which has been hearing from senior former politicians involved in negotiations that culminated in the Good Friday peace deal in April 1998.
Mr Major said any attempt to force unionists into a united Ireland will lead to new violence.
He said former Taoiseach Albert Reynolds “would have preferred me to become a persuader for unification”.
“That I couldn't and wouldn't do,” he said.
“And the reason is clear,” he added. “If I had done so, it would have broken the peace process, because the unionist community would never have co-operated in any way.
“It was clear that unification, if it was to come about, would have to be with open consent, because for the unionist community, any attempted duress would have failed and led to renewed violence. That was - and remains - true,” he said.
Mr Major was prime minister and Britain's Conservative Party leader from 1990 until 1997 and delivered the Downing Street Declaration which paved the way for the signing of the Good Friday Agreement.
Mr Major said that it was “very important that every effort is made to solve the problem of the Protocol, which was perhaps one of the least well-done negotiations in modern history and ensure that the Protocol problem ceases to be an inhibitor to the [Northern Ireland] executive meeting”.
It is “not beyond hope to get an agreement on the Protocol,” he said. “It has to be put right and the sooner it is put right the better.”
However he said he doubted if there was “a perfect solution”, but that any discussions needed “a degree of flexibility on both sides of the negotiation” in London and Brussels.
“It should be dealt with as a degree of priority to enable the executive to meet again,” he said, which would “go a long way to improving the relationship between London and Dublin”.
Urging better relations and engagement in the North, Mr Major said that “the present prime minister and Northern Ireland secretary are more open to improving relationships and dealing with the problems that are currently outstanding than has been the matter of late”.
He was speaking after Finance Minister Michael McGrath suggested that Ireland and Britain have a shared determination to secure an agreement on post-Brexit negotiations.
In one of the more pointed exchanges at the committee, Mr Major and Sinn Féin MP John Finucane clashed over allegations of collusion between British security forces and loyalist paramilitaries in the death of his father solicitor Pat Finucane in 1989.
Mr Major also refused to comment on the controversial Legacy Bill, currently working its way through the House of Lords. He said it would be "unwise" to comment on complex legislation that he was not across the detail of, given he left Parliament almost 25 years ago.
That bill has been the subject of much criticism on the grounds that it gives impunity from prosecution to the British security forces for crimes committed in Northern Ireland.