NSW school 'hoax' threats continue: report

A police operation is underway on Sydney's northern beaches where a school has reportedly been threatened following days of hoax calls to NSW schools.

Threats against NSW schools have continued for the fourth consecutive day as police warn about hoax calls from overseas.

Police confirmed an operation was underway at Mona Vale on Sydney's northern beaches, on Wednesday morning.

Students from Mona Vale Public School have reported been evacuated - the second time in four days, with the school also evacuated on Friday.

"There is no evidence these are anything other than hoaxes designed to cause unnecessary disruption and inconvenience," NSW police said.

At least two schools on the state's Central Coast have also been evacuated on Wednesday, with police saying a number of schools across NSW have been affected.

Schools in Queensland and Victoria have also been disrupted on Wednesday.