Fearghal McKinney, head of the BHF in Northern Ireland, said it is important to correct the record as the charity has suffered reputational damage due to the fall out.

“This caused enormous distress and anxiety among our staff and unwavering supporters,” he added.

On Wednesday, O’Neill said there were lessons for a lot of people in terms of “due diligence for an employer when they take on an employee”.

Mr McKinney said O’Neill has “expressed regret” about the comments.

“It was quite clear that whenever comments were made about due diligence that there was only one other organisation that employed him since he was employed by Sinn Féin, so clearly there was a reflection on us,” he told BBC News NI.

“We need to have support from the public – close supporters, volunteers, staff,” he said, adding that “any damage caused to that at all” can “undermine the good work” of the charity.

“When this happened and there was damage caused, as we saw it, to our reputation, added damage we thought around the public comments that were made, we had to do something to make sure that the record was put straight,” Mr McKinney said.

“We’re content that we have done everything in our power in order of keeping all our supporters, all our staff and the wider public that’s connected with us safe and they know that that’s what the standard that the British Heart Foundation applies.”

The work references were provided three months after McMonagle was dismissed from the party while under police investigation.

Sinn Féin said this happened without clearance from the party and described the press officers’ actions as wrong and unacceptable.

Seán Mag Uidhir and Caolán McGinley have resigned from their roles at the party.

When asked if the charity was aware of the reasons for McMonagle leaving Sinn Féin, Mr McKinney replied: “We knew nothing.”

The leaders of the Democratic Unionist Party (DUP) and the Social Democratic and Labour Party (SDLP) have called for O’Neill to be questioned in the Assembly over the issue.

Mr McKinney said he spoke with O’Neill on Saturday morning and that she offered “words of regret and apology about what has happened”.

He said in the phone call he outlined the hiring process McMonagle went through, as well as the “robust internal investigation” that he said took place after the charity learned of the charges.

“Michelle O’Neill agreed recent comments by her and party colleagues questioning the BHF’s due diligence process were unhelpful, and she expressed regret for the damage and upset this has caused to our dedicated staff and supporters,” he told BBC’s Good Morning Ulster programme.

“I wish to reiterate that the BHF is confident we undertook all necessary statutory and moral duties required throughout this entire process.

“The tone of the phone call and the words of the phone call was sufficient for us to feel confident that, in fact, the situation and the record has been put absolutely straight.”

“We reached out to Sinn Féin to let them know that the comments around the nearness of their knowledge about this was not the reality and that in fact we had been talking to a HR official in Sinn Féin over a year before,” said Mr McKinney.

O’Neill confirmed on Saturday that a human resources (HR) manager had been contacted by the charity in August 2023, but added the party’s leadership had not been made aware of this.

In a statement on Saturday, she described this as “a serious omission”.

Previously, Sinn Féin minister Conor Murphy told BBC News NI the party had only been aware of the references since 25 September 2024.

O’Neill said she apologised for the hurt and distress caused by the press officers who provided the references and reiterated Murphy’s claim that the party leadership was unaware of the references until recently.

“On Wednesday 25 September 2024, Sinn Féin and I were informed that two press officers, who were former colleagues of Michael McMonagle, had provided employment references for him,” O’Neill said in the statement.

“I am absolutely appalled and horrified that this occurred,” she continued.

“These references were given without the knowledge or authorisation of the party.

“Under no circumstances would the party provide a reference, for work or otherwise, for Michael McMonagle.”