On Sunday, the leader of Ireland's Sinn Fein faction, which was once the political wing of the Irish Republican Army (IRA), apologized for the assassination of Prince Philip's uncle Louis Mountbatten by the IRA.

In 1979, the Irish Republican Army (IRA) assassinated Philip's mentor as part of a decades-long war between Irish republicans and those who wanted Northern Ireland to remain under British control.

Mary Lou McDonald's remark came a day after Queen Elizabeth II's husband, Prince Philip, was laid to rest after passing away on April 9 at the age of 99.

McDonald told Times Radio, "Of course I'm sorry that happened; of course that's heartbreaking."

“I am pleased to reiterate that your queen buried her beloved husband over the weekend,” she said.

McDonald's predecessor, Gerry Adams, had said at the time that Mountbatten was a legitimate target, but it was the first time an Irish republican political leader apologized for the bombing.

When the IRA blew up Mountbatten's yacht in the Irish village of Mullaghmore, three other people were killed, including Mountbatten's 14-year-old grandson and a 15-year-old boy.

Mountbatten was also a mentor to Prince Charles, Philip's uncle.

“My work and I think Prince Charles... will totally appreciate it,” McDonald said on Sunday, “is to lead from the front now, in these times.”

“It is our collective responsibility to ensure that no other child, no other family, regardless of who they are, experiences the kind of trauma and heartbreak that was all too prevalent sadly on all sides on this island and beyond,” she said.

Around 3,500 people died in the dispute between unionists and nationalists over Northern Ireland's future, which ended in a historic peace settlement in 1998.

After a week of protests, Irish Prime Minister Micheal Martin cautioned against a "spiral back" into sectarian violence in Northern Ireland, raising concerns about the fragile agreement's future.