LONDON: Over 400 schools in England were today targeted with bomb hoax emails that claimed a device would be detonated on the grounds unless online payments were made to an address.
Scotland Yard said the malicious communications were under investigation but ruled out any threat to life.
These are currently being treated as hoaxes.
At this stage there is no evidence to suggest that this is terror-related, the Metropolitan Police said.
Schools in London, Manchester, Northumbria and North Yorkshire were among those that received the email, which demanded 5,000 USD and warned against calling the police.
A number of schools were evacuated while the threat level was assessed before resuming normal routine.
"We have spoken to all schools who have contacted us, reassured them that there is no need to evacuate and offered them security advice," said Detective Superintendent Tony Cockerill from Humberside Police, which received reports of 19 schools being targeted by the hoax emails.
Greater Manchester Police's Assistant Chief Constable Vanessa Jardine said: "I want to assure you that we are working closely with all of the schools to ensure the safety of pupils and staff.
"We are carrying out extensive enquiries to understand the full circumstances and although there is not currently believed to be any direct threat, as with any report of this nature, they are all being thoroughly investigated.
" Police forces in Cumbria, Cambridgeshire, Humberside, Hertfordshire, Lincolnshire, Derbyshire and Avon and Somerset also issued statements saying schools and colleges in their areas had been targeted.
"Our cybercrime unit detectives, supported by local officers, have looked at these incidents and it is not believed there is any genuine threat," North Yorkshire Police said.
The emails are believed to originate from the US, written mostly in English but also including some Arabic sentences.
The UK Home Office and the Department for Education advised any school that receives the email to contact their local police force.