Dozens of schools with nearly 40,000 pupils have suffered a 'vicious' cyber attack, it is reported.
The government’s National Cyber Security Centre issued an alert about a spike in so-called ransomware attacks affecting schools last Tuesday, March 23.
Harris Federation, which has 37,000 pupils in 50 academies in and around London, has since reported they have suffered a ransomware attack.
Though measures were in place to protect their systems, their servers have been impacted, a statement says.
A statement to parents and pupils said: "A ransomware attack means that cyber-criminals have accessed our IT systems and encrypted, or hidden, their contents.
"We are at least the fourth multi academy trust to have been targeted in March.
"The attack came to light on Saturday 27th March, and we have been working through the weekend to begin resolving it.
"This is a highly sophisticated attack that will have significant impact on our academies but it will take time to uncover the exact details of what has or has not happened, and to resolve.
"In addition to using the services of a specialised firm of cyber technology consultants, we are working closely with the National Crime Agency and the National Cyber Security Centre."
As a precaution the academies have temporarily disabled their email system.
The statement continues: "Our telephone systems, which run on the internet, have also been disabled but each academy switchboard has been diverted to a mobile telephone.
"Switchboard services are therefore very limited and we would ask that you temporarily avoid telephoning us or any Harris academy other than to report absence or in emergencies."
Where pupils have Harris Federation devices, these have been disabled as a precaution and cannot currently be used.
