A memorial service is being held in Northern Ireland today Sunday for an IRA member who was hanged nearly sixty years ago for his part in the killing of a police officer.

The body of the man, Tom Williams, was laid to rest in a family plot on Wednesday after a long campaign to have it removed from a grave in the grounds of a Belfast prison.

Today's ceremony, which is being organised by the IRA's political wing, Sinn Fein, is taking place as the Northern Ireland peace agreement is coming under increasing strain.

On Saturday the mainly Protestant Ulster Unionists -- who want to retain links with Britain -- warned that unless the IRA began decommissioning weapons by the end of the month, the province's power-sharing executive would collapse. The Sinn Fein chairman, Mitchel McLaughlin, accused the Unionists of seeking to undermine the peace agreement.

From the newsroom of the BBC World Service