Pupils returned to Holy Cross Boys' Primary School yesterday after the Easter break. Picture by Ann McManus

THE bomb left outside a primary school in north Belfast is believed to have been dumped by dissidents who believed they were under surveillance by police.

The device, contained in a metal cannister, was defused in the early hours of Sunday at the gates of the Holy Cross Boys' PS in Ardoyne.

Some people, including elderly residents and a six-year-old girl, had to be evacuated from their homes while army technical officers worked on the bomb throughout the night before removing it for forensic examination.

Police have said it was discovered by officers on foot patrol.

However, local sources say a police helicopter had hovered above the area beaming spotlights down for a considerable time before officers arrived on the ground, leading to speculation that they were tipped off about the whereabouts of the device.

It is claimed the bomb was dumped at the gates of the school after those transporting it - believed to be members of the organisation known as the 'IRA' or 'New IRA' - suspected they were under surveillance and fled.

While it has yet to claim responsibility, it would be the group's first act since re-iterating its intention to continue its violent campaign in an Easter statement.

The Irish News understands that the bomb contained a commercial explosive and was to be detonated by a trip wire which had not yet been attached.

It is thought it was to be transported a short distance and police lured to the scene before being exploded from a vantage point.

While police have said the bomb "wasn't a large device, but was significant in terms of shape", the make-up is thought to be similar to those previously used by the Provisional IRA.

The principal of Holy Cross, Kevin McArevey, condemned those responsible yesterday.

"Thankfully it didn't explode and no-one was hurt, but there could have been loss of life and damage to the school," he said.

"School should be a safe and secure place for children and also for all those who work here. We're the biggest employer in the local area and so this negativity is not what needed in the Ardoyne community.

"The school has always been a part of the community and worked with the community. We work very closely with all organisations, politicians and Church to promote a positive image, through education, music and sport.

"We have an open door policy and many people would know that.

"Regardless of circumstances, for this device to be left at our front doors when I had 454 children showing up for school on Monday morning is unacceptable."