LONDON — The Irish Republican Army-linked Sinn Fein party says one of its leaders, Martin McGuinness, will meet Queen Elizabeth II next week — a once-unthinkable symbol of progress toward peace in Northern Ireland.

McGuinness, a former IRA commander, has been invited to attend an event with the queen in his role as deputy first minister of Northern Ireland.

The queen and her husband, Prince Philip, will visit Northern Ireland on Tuesday and Wednesday as part of her United Kingdom-wide tour to celebrate her 60 years on the throne.

Sinn Fein leaders declined to meet the queen last year during her first state visit to the neighboring Republic of Ireland, arguing it was still too soon.

But party President Gerry Adams said Friday the party has decided McGuinness should meet the monarch.

“We don’t have to do it. We’re doing it because it’s the right thing to do, despite the fact that it will cause difficulties for our own folk,” Adams said.

“But it’s good for Ireland. It’s good for this process we’re trying to develop. It’s the right time and the right reason.”

Buckingham Palace said it understood McGuinness had been invited to Wednesday’s event in Belfast for the Co-operation Ireland charity.

It was a sign of progress toward peace that the royal visit was announced several weeks in advance.

The queen has regularly visited Northern Ireland over the past four decades of bloodshed, but none of her previous visits had been announced even a minute ahead of time to minimize the risk of attack.

The threat was very real, as evidenced by the Provisional IRA’s 1979 assassination of Lord Louis Mountbatten, Prince Philip’s 79-year-old uncle. Several small IRA splinter groups still launch gun and bomb attacks in Northern Ireland.

But political reconciliation has advanced rapidly since 2005, when the Provisional IRA renounced violence and disarmed, and 2007, when Sinn Fein entered a power-sharing government alongside Northern Ireland’s British Protestant majority. Their unlikely coalition has proved remarkably stable.