The hoax packages were intercepted at Royal Mail's main sorting office

It is understood a worker at the Royal Mail sorting office in Mallusk discovered a suspicious package at about 2130 GMT on Monday.

Army bomb experts were called to the scene on the outskirts of north Belfast.

The area was evacuated while they carried out a search.

Hoax devices

Three more suspect devices were then discovered.

All four devices were later declared hoaxes.

Policing Board chairman Sir Desmond Rea said the incident was "despicable".

He said: "I utterly condemn devices being sent to members of the DPP, in this case Strabane.

"This is another despicable act and all right-thinking people, not simply members of this board, would wish to condemn it utterly."

West Tyrone SDLP MLA Eugene McMenamin, said one of the hoax devices had been addressed to him and another had been addressed to a party colleague.

I don't expect everyone to agree with me, but I take my stand on policing openly and I preach it publicly Eugene McMenamin

"If the brave patriots who use the Royal Mail to do their work think they are going to achieve something in this way, they can think again," Mr McMenamin said.

"Politics is about changing people's minds, convincing them of your case or your cause, but this isn't politics.

"I don't expect everyone to agree with me, but I take my stand on policing openly and I preach it publicly."

In August 2004, seven suspicious packages addressed to members of the Policing Board and the police ombudsman were intercepted at the Mallusk office, which is Northern Ireland's main sorting office.

Letter bombs

Royal Mail staff in Coleraine intercepted an eighth package, addressed to a politician.

The packages contained a powder which was not thought to pose a credible risk.

In July, dissident republicans were blamed for five letter bombs intercepted at the Mallusk office.

One of the devices was addressed to the governor of Maghaberry Prison in County Antrim.