JAILED dissident Ciaran 'Zack' Smyth is suspected of being behind a New IRA plot to mortar bomb a Belfast PSNI station.
Sunday Life understands that this, along with death threats he is alleged to have made against Sinn Fein's Michelle O'Neill and Gerry Kelly, was the key reason for the recent suspension of his early release licence.
Last month the PSNI dramatically increased its vehicle checkpoints on the Crumlin Road in the north of the city after intelligence warned of a New IRA bomb attack on Musgrave Street station in the city centre.
The information was passed to the PSNI by MI5's counter-terrorism command and came from a terror gang informant, who also disclosed that the mortar bomb had been stashed in Ardoyne.
Ex-Provisional IRA prisoner Smyth is alleged to have been central to the bomb plot.
A source said: "Zack was boasting about it in pubs in west Belfast in front of people he hardly knew, then he was openly threatening Sinn Fein leaders while he had drink in him. He basically talked himself back into jail."
Michelle O'Neill and Gerry Kelly were warned in February that they were under threat from the New IRA - claims denied by the hardline republican group.
But it was not until Smyth was linked to a possible New IRA bomb bid on a Belfast PSNI station that his early release licence was revoked a fortnight ago.
The 60-year-old now faces the prospect of serving the remaining seven years of a 14-year sentence for invading the home of and burgling a man in his 80s.
A security source said the PSNI Tactical Support Group's ebony and navy sections were involved in trying to intercept the bomb to which Smyth has been linked.
"Every unmarked van or suspicious vehicle, especially in north Belfast, was being stopped and searched," explained the insider.
"It is believed the New IRA was keeping the ordinance in Ardoyne."
The mortar bomb was identified as a Mark 15 type, which was known as a 'barrack buster' during the Troubles.
An early version of the devastating weapon was used by the Provisional IRA to bomb a 1991 meeting of the Cabinet at Downing Street in London.
It usually consists of home-made explosives packed into an empty gas cylinder and fired from a range of up to 275 metres.
The New IRA has been behind several failed bomb bids on security targets in recent years.
Last September cops acting on a tip-off discovered a primed mortar bomb aimed at a PSNI station in Strabane. This led to searches in the Creggan area of Londonderry, which located another booby-trap bomb.
When Zack Smyth was active in the Provisional IRA in west Belfast, his gang carried out several bomb attacks.
Smyth, jailed for nine years for IRA activity in the 1970s and who took part in the blanket protests, is currently caged at the Roe House dissident republican wing of Maghaberry Prison.