Some 6,300 schools across Italy and more than 700 in Scotland and Northern Ireland have received bomb threats, according to local authorities.
In Italy a number of buildings were evacuated as a precaution but Prime Minister Giorgia Meloni said checks so far had not indicated any evidence of “concrete danger”.
“These reports appear rather linked to a strategy intended to cause alarm and concern,” she said on Facebook.
Scotland’s education secretary Mairi McAllan said there was no risk to the public and specialist cyber-crime officers were working to identify the source of the messages. In Northern Ireland education officials told schools to remain open unless otherwise advised by police.
It is unclear whether the incidents are connected.
“As a parent and as a constituency MSP I understand just how concerning this will be for parents, for pupils, for carers and for school staff,” McAllan said.
Scottish police had earlier said that the warnings were “immediately assessed” as hoaxes. However some local authorities confirmed that some schools had been evacuated.
“Our advice is that there is no requirement to evacuate schools or keep children away from education based solely on the content of the emails,” Police Scotland said.
Italian officials said a single email appeared to have been sent on Wednesday to the inboxes of 6,300 out of a total of 7,476 state schools, and private schools were unaffected.
The message, said to be from a certain “Mikhail Andropov, leader of Vilayat di Misoginistan”, caused alarm in many schools.
Italy’s Education Minister Giuseppe Valditara said the incidents were probably a “cyber-attack, not a genuine risk”, adding that there appeared to be a clear strategy behind the rash of threats in across Europe targeting flights, supermarkets and even hospitals.
Italian airports along with airlines elsewhere in Europe were hit by a series of bomb hoaxes last week that prompted a series of scares, evacuations and widespread disruption.
Although a number of threats were claimed by an extremist misogynistic group, it later denied any link to the false warnings.
