The PSNI has deployed 350 officers, supported by MI5 and the gardai, in the operation to catch the dissident republican killers of two soldiers and a PSNI constable, the Belfast Telegraph can reveal.

According to a senior source, the scale of the investigation is an indication of the determination to deal with the dissident threat.

The Telegraph can reveal details of the massive police hunt to find the Real IRA gang which killed Sappers Mark Quinsey (23) and Patrick Azimkar (21) at Massereene Army Barracks on Saturday and the CIRA terrorists who gunned down 48-year-old Constable Stephen Carroll in Craigavon on Monday night.

While senior police officers do not believe that the terror groups co-ordinated the two attacks, they do believe that the Craigavon attackers were motivated by the scale and impact of the Army barracks murders.

“One success spurred on the other,” a senior security source told this newspaper.

However, he added that there was no suggestion of one group saying to the other: “We’ve got a Saturday spectacular. You get something for Monday.”

The number of PSNI officers deployed does not include those involved in undercover surveillance duties.

The weekend killings at the Army barracks in Antrim have been described as a “classic assassination” — demonstrating training or experience on the part of the gunmen.

Asked if he believed those gunmen were from the Antrim area, the senior security source said: “No — that wouldn’t be the obvious lead. That wouldn’t be where the investigation is taking us.”

The source said the shooting in Craigavon was “of a different nature” — and it was “careful enough in its execution”.

In August last year, in the same town, dissidents fired four shots at a police cordon. Not a burst, but “four deliberate shots,” a security source said — adding that Monday’s attack in which Constable Carroll was murdered was “not a new modus operandi” from the Continuity IRA.

Now informants and other intelligence sources are being used to help identify the killers.

Dissident republicans are understood to be using eastern Europe and the criminal underworld in Dublin to arm their groups.

A security source said there are “guns available at a price”.

“What is apparent is they (the dissidents) have spent a considerable amount of time around logistics, including cash to purchase,” the source said.

“There is a constant effort on the part of the dissidents to obtain weapons.”

Those in intelligence have a clear picture of dissident leaders.

“The leaders are identifiable to us,” the source said.“There are a couple of prominent ones here (in Northern Ireland), (but) the weight of the leadership resides in the south,” he added.