A bomb disposal squad from Northumbria Police has been sent to Ponteland High School to carry out a controlled explosion.
It is among a number of schools across the country that have called their local force in recent days after a fresh reminder was issued over the storage of a chemical.
The Explosive Ordnance Disposal (EOD) team arrived after students had left for the day.
The chemical 2,4-dinitrophenylhydrazine, known as ‘DNP’, is used as a reactive agent in lab tests.
The reminder from CLEAPSS – the Government’s science and technology advisory service – was recently issued by the Department for Education after it received a number of calls from schools about the chemical.
A Northumbria Police spokesman said: “EOD are at Ponteland High School to carry out a controlled explosion as per CLEAPSS guidance.”
A Department for Education spokeswoman said: “We have contacted schools to remind them of the importance of storing chemicals for practical science activities carefully.”