Mary Lou McDonald (fourth left) at the Peter McNulty commemoration last week

Peter McNulty was killed in a premature bomb explosion during an attack on Castlewellan RUC base on January 26, 1972.

Ms McDonald, along with Sinn Fein MP Chris Hazzard and other party representatives, attended a wreath-laying ceremony for the 47-year-old in the Co Down village on Friday.

A picture on Twitter shows the Dublin Central TD looking on as a piper plays a lament to mark the 46th anniversary of the IRA man’s death. She later retweeted the post.

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Mary Lou McDonald

Ms McDonald’s attendance at the event has drawn the ire of unionists, with TUV leader Jim Allister accusing her of “glorifying a terrorist bomber”.

Meanwhile, former Ulster Unionist leader Sir Reg Empey claimed her presence at the event showed Ms McDonald was “bending the knee to Sinn Fein’s military wing”.

It comes less than two weeks after Sinn Fein MP Barry McElduff resigned after posting a video on Twitter, in which he appeared to mock victims of the Kingsmills massacre.

SF deputy leader Ms McDonald is set to replace Gerry Adams as president at a special party conference next month.

Mary Lou McDonald

She was the only candidate nominated for the role.

North Antrim MLA Mr Allister said Ms McDonald’s decision to commemorate an IRA bomber shows “nothing has or will change with IRA/SF”.

He added: “Here we have Mary Lou McDonald and two Sinn Fein MPs glorifying a terrorist bomber who sought to bring death and destruction to Castlewellan.

“Just over a week from all the cant and hypocrisy about respect, following the McElduff PR disaster, usual service has been resumed with the glorification of IRA terrorism still a top priority.

“Those trying to placate Sinn Fein in the current talks, please note.”

South Down’s sole unionist MLA, Jim Wells, told the News Letter that events commemorating terrorists “are a barrier to reconciliation”.

The DUP man added: “Only a few days after Mary Lou McDonald was talking about her ‘unionist brothers and sisters’, she has chosen to attend an event eulogising someone killed by his own bomb as he sought to carry out murder.

“Whilst we should be looking to the future, there are some who continue to glamorise the terrorism which blighted our past.”

Lord Empey claimed the move by Ms McDonald indicated there would be “no departure from the Sinn Fein of old under her leadership”.

UUP colleague Robbie Butler MLA added: “SF’s president-elect has failed to demonstrate to unionism that she is up to moving politics forward in Northern Ireland.”

In a statement to the News Letter yesterday evening, a Sinn Fein spokesperson said: “Republicans recognise that there was hurt throughout all the community as a result of the conflict and the Good Friday Agreement affirms that everyone has a right to remember their dead in a respectful and dignified manner.

“There is no hierarchy of victims. Peter McNulty’s death was a huge personal loss for his family and the nationalist community in the area.