Bellshill Academy became the latest in a string of schools across the country to be targeted. Primary 6 pupils were on a visit to the school when it had to be evacuated.
A spokesman for North Lanarkshire Council said: “The school was evacuated around 10am and a thorough search of the building was carried out by the emergency services.”
Pupils were allowed back to their classes before lunchtime. There was a similar incident at Taylor High School in New Stevenston on May 31.
Earlier this month police arrested a boy aged 15 in relation to hoax calls to schools in Lanarkshire, Glasgow, Clydebank and Campbeltown.
At the weekend another arrest was made as a boy of 16 was quizzed over threats to schools in Ayrshire.
Police confirmed “nothing untoward” was found during the search of Bellshill Academy and there was no information to suggest it was anything more than yet another hoax.
A spokesman added: “We take hoax calls incredibly seriously. The disruption this and other such incidents have caused to the teaching staff, emergency services, local residents and, in particular, the schoolchildren involved cannot be overstated.
“If anyone has any information relating to this incident please report it at any police office, via 101 or through Crimestoppers on 0800-555111.”
Parents hit out at the hoax on Facebook, saying children had been frightened and calling for stern action to be taken against the culprit.
One mum said: “My Primary 6 child was there at the time on a visit. People don’t realise how much kids worry about this kind of thing, hoax or not.
“Hope whoever is caught gets more than a caution. Not funny!”
Another posted: “My daughter there today on her school visit. This is shocking! Scum people doing this to kids. So glad I went up to make sure she’s ok although I would rather she was home with me.”
Another angry parent wrote: “My wee girl was there with her primary and my older daughter goes to the academy. Kids must have been scared - these idiots need to be caught and locked up.”