The Red Hand Defenders, a cover name for the Ulster Defence Association, has claimed responsibility for planting a pipe bomb outside the Catholic Holy Cross school in north Belfast today.
The device, attached to the school gates, was safely defused as children and their parents took an alternative route to the school.
Sinn Fein's Gerry Kelly has described the incident as despicable and called on Ulster Unionist leader David Trimble to mediate and try to prevent further attacks.