Schools in Cambridgeshire have been targeted with a bomb hoax.
Police are investigating after 'a number' of threatening emails were sent to schools across the country.
A number of schools were believed to have been targeted including some in Cambridgeshire, police confirmed.
The National Crime Agency confirmed that emails had been sent in a short statement.
It said: "We are aware of a number of threatening emails being sent to schools and are investigating alongside our partners in the police.
"We understand that these types of emails can be distressing and while we take the communications extremely seriously we must stress there is no credible threat."
We are aware of a number of threatening emails being sent to schools and are investigating alongside partners. We understand that these types of emails can be distressing and while we take the communications extremely cautiously, we must stress there is no credible threat (1/2)
— NationalCrimeAgency (@NCA_UK) May 8, 2018
A spate of bomb hoaxes hit the county's schools April 13, but police said the threats are not being treated as "viable".
The disruptive warnings, delivered by email, are part of a wave of similar messages delivered to other schools around the country.
As well as in Cambridgeshire, there are reports of school hoaxes in Norfolk and Lincolnshire.
In East Yorkshire, more than a dozen schools – mostly primaries – were closed or evacuated after 'bomb threat' emails were sent out last month.
The threatening emails in April came less than a month after more than 400 schools across the UK received hoax bomb threats, forcing some to evacuate.
A threatening email, which was also sent to some schools in Cambridgeshire, is reported to have said: "This is a message to everyone. We have sent in a student with a bomb. The bomb is set to go off in 3 hours time. If you do sent $5,000 USD to [email protected]
"If you do not send the money! We will blow up the device. Our site has all the information needed.
"If you try to call the cops we WILL blowup the device on the SPOT! ANY attempt at defusing it your self will cause it to explode."
Anyone with information should contact police on 101 or call Crimestoppers, anonymously, on 0800 555111.