An Army bomb unit at the scene of the explosion at Palace Barracks

An Army bomb unit at the scene of the explosion at Palace Barracks

A major security review has been ordered by police and Army chiefs after a dissident republican bomb exploded inside one of Northern Ireland's most heavily fortified military bases.

No one was injured in the attack on Palace Barracks in Holywood but an immediate inquiry has been launched into how the terrorists managed to breach the base's stringent security.

As well as military personnel, the base houses MI5's Northern Ireland headquarters.

The blast was caused by a letter bomb - one of the Provisional IRA's favourite terror tactics - and detonated in a Royal Mail van.

From the roads around Palace Barracks, there was little indication that dissidents had carried out their second attack there in the past five years

Yesterday's bomb went off after a Royal Mail driver had gone through a number of checkpoints at the entrance to the barracks.

The blast started a fire in the van around 10.30am but it was more than five hours before the PSNI gave any details and another three before they confirmed it was a bomb.

Supt Karen Baxter said: "Due to the damage caused by fire and water the exact nature and make-up of the device that caused the explosion has yet to be established

"Although we have no information to suggest there may be other similar packages in the postal system, we are working closely with Royal Mail to mitigate any potential risk."

The police described the explosion as small, but it still caused extensive damage to the van.

The Northern Ireland Fire and Rescue Service said the blaze spread to two cars and three garages nearby. Three fire appliances tackled the blaze for more than two hours.

The PSNI's initial statement said only that it was in attendance at a fire in a postal van at the barracks. It added: "Although the cause of the fire has yet to be established and investigations are ongoing, a suspected explosion is one line of inquiry."

A Royal Mail spokesman said: "Thankfully our postman was not in the vehicle at the time of the incident and is safe and well."

At first the MoD would only say there had been a vehicle fire within their military base.

However, politicians were in no doubt that it was a terrorist attack.

Local DUP Assemblyman Gordon Dunne said the incident "had been a serious threat to security".

He added: "The community are very shocked and concerned about what has happened today."

Ulster Unionist MLA Leslie Cree, who represents North Down, described the bombers as fascist-style criminals who sought to rule by fear.

He added: "The people responsible have nothing to offer anyone in this society. They dare not face the electorate because they know they face humiliation and rejection."

Alliance councillor Andrew Muir said he was appalled and called on all politicians to unite in signalling that Northern Ireland had no desire to return to the past.

He added: "Those days are over and we must not allow the thugs behind the incident to succeed in dragging us back."

The bomb may not have been a big one, but the repercussions of the security breach will be massive. A number of letter bombs have been intercepted on their way to security force targets in the recent past.

The PSNI has repeatedly warned that the threat posed by dissident republicans was high in recent months.

Less than a fortnight ago what was described by police as a mortar-type device was found in a cemetery in Strabane.

Three days later a gun was found not far away during a police investigation into dissident republican activity in the Tyrone town.

Earlier this week a bomb that exploded with no injuries in a bin in the Skeoge Road area of Derry was branded by police as an indiscriminate attack with the potential to kill.

In May the police assessed the dissident threat in Northern Ireland as "severe" and their patrols and checkpoints were stepped up.

Assistant Chief Constable Stephen Martin said the increase in security had been ordered in the light of four attacks in Belfast and Londonderry over the preceding two weeks.

In Derry two of the bombs were left close to the Caw Army base.

Palace Barracks was last targeted by dissidents in April 2010 when a car bomb exploded at the back of the base.

On that occasion a taxi driver was forced to take his hijacked cab to Holywood after his family were held hostage.

The bomb exploded as nearby homes were being evacuated but there were no serious injuries.

The attack, claimed by the Real IRA, had been timed to coincide with the transfer of power for policing and the judiciary to the Stormont Executive.

Belfast Telegraph