Parents were advised on Wednesday morning that friable loose-fill asbestos had been found on rafters inside the school's heritage building as part of works to replace the building's 1970s-era faux slate roof during the school holidays.

It is not known how long material had been exposed to the environment for.

Further testing revealed some library books that had previously been housed in the building also tested positive for asbestos. The books have since been destroyed.

The Newcastle Herald has been told that teachers who were advised of the hazard when they returned to work on Tuesday were shocked and considered walking out.

Compounding the crisis is the fact that teaching materials, including computers, smartboards, musical instruments and maths resources, that were stored in the building have also been destroyed.

A clearance certificate for the school was only issued at 7am on Wednesday.

Department officials who spoke to parents did not rule out the possibility that children may have been exposed to asbestos contamination.

"My son helped moved equipment from the heritage building to the new buildings but the fact it was found on the books is just too much," one parent said.

The school's principal and departmental officials took parents aside after the school's first day of school assembly to break the news about the contamination.

"I wanted more information and I wanted it quickly and I'm concerned that that doesn't appear to have happened," Simonne Pengelly said.

"There is a strong possibility that we will need to register our children on the dust diseases register like everyone else in the state who has been exposed to asbestos.

"That's a bit of a surprise when you send them to school to find out that's the outcome."

P&C president Lisa Piefke said parents had been kept in the dark about the unfolding crisis.

"[The parents] were really concerned nothing had been said before we went away on holidays," she said.

"The undertaking was that everything was under control the asbestos management plan was in place. There shouldn't have been any concerns about the replacement of the roof. Today was a shock."

Surrounding residents were equally scathing of the way the project was handled as well as the risk of drift contamination.

"I asked whether they were going to encase the building in plastic and if they were going to wash down the surrounding buildings," a resident said.

"They told me it wasn't part of the environmental standards that they had to comply with."

The NSW Teachers Federation said it was concerned about the situation.

"Asbestos is a serious issue and every instance needs to be investigated thoroughly," organiser Jack Galvin Waight said.

"The department has a responsibility to immediately investigate claims of suspected asbestos in schools and ensure a safe working environment for both staff and students."

A Department of Education spokesman said clearance certificates had been received from independent hygienists for all buildings and the department was confident the school was now safe for students and staff.

Ongoing air quality monitoring was being undertaken as a precaution.

"The department reiterates that clearance certificates have already indicated that the school is safe," the spokesman said.

"Staff have also requested further validation samples on equipment and resources located throughout the school. Further testing will commence this afternoon."

Newcastle MP Tim Crakanthorp was assured in September 2019 that no schools in his electorate contained friable asbestos.

He has called on the minister to attend the school and meet with parents.

"This building has a long history of asbestos contamination, in fact, that is the exact reason works were being undertaken at the school," he said.

"We need to know how many kids have been exposed and what supports are available to staff and parents now that they are having to deal with this news.

"The Education Minister needs to immediately come to Newcastle to face these parents, provide an assurance that the school is safe and deliver a full explanation."