DUBLIN, Ireland — The major Northern Ireland Protestant paramilitary group, the Ulster Defense Association, announced yesterday it was formally renouncing violence, but a commander said the group would not surrender its weapons to international disarmament officials.

The group, which has an estimated 3,000 members across hard-line parts of Northern Ireland, has loosely observed a ceasefire since 1994, but until now has refused to surrender a single bullet or bomb — a major objective of a 1998 peace accord.

It is the last of Northern Ireland’s underground armies to renounce violence. The Irish Republican Army, the major Catholic paramilitary, did so and disarmed in 2005.

The group said in a statement that at midnight yesterday it would “stand down with all military intelligence destroyed, and, as a consequence of this, all weaponry will be put beyond use.”

The UDA’s south Belfast commander, Jackie McDonald, confirmed the group would not surrender its weapons to international disarmament officials.

The UDA appeared to be following the Ulster Volunteer Force — the other major Protestant underground army — which said in May that it had placed its weapons under the custody of senior members and “beyond the reach” of rank-and-file members. The UVF did not surrender any to John de Chastelain, the retired Canadian general who since 1997 has been trying to oversee paramilitary disarmament in Northern Ireland. Prime Minister Ahern of Ireland welcomed the UDA’s move, but said it now must cooperate with the Independent International Commission on Decommissioning and surrender its weapons.

His comments were echoed by the senior British government official in the province, Northern Ireland Secretary Shaun Woodward. “They will be judged by their actions, not their words,” Mr. Woodward said.