Minor scuffles amid a significant Garda presence have been reported near a Dublin cemetery where a memorial for those killed in Ireland's 1916 Easter Rising was being unveiled.
Two people were arrested, according to a report in the Irish Times.
The memorial at the Glasnevin cemetery has sparked controversy because it includes the names of British soldiers killed in the uprising - a small protest line formed outside the event on Sunday as a result.
Acting Irish Taoiseach Enda Kenny attended the service and laid a wreath at the memorial.
A minute's silence was observed before the last post was sounded and the Irish Tricolour raised from half to full mast.
The memorial is part of a series of commemorative events marking the 100 years since the uprising against the British.
It lists the names of the 488 people known to have died in the rising, including 119 British soldiers, some of whom are buried in Glasnevin.
The Glasnevin Trust insisted the memorial is an attempt to present the historical facts, without hierarchy or judgment.
John Green, the trust's chairman, who spoke at the service, said the wall reflected modern Ireland.
"Behind each and everyone of these lost lives is a story of heartbreak, no matter what side the person served on or indeed for those innocently caught up in the conflict," he said.
"One hundred years on we believe this memorial reflects the time we live in, with the overwhelming majority of the Irish people wishing to live in peace and in reconciliation.
"But it is for each visitor to take from the wall what they wish."
The names of the dead are engraved on the reflective black granite stones.
The majority of those killed in the event - 268 - were civilians caught up in the violence.