Several schools around Greece's capital Athens were evacuated Wednesday after a bomb hoax that was traced to a Russian server, police said.
"At least 35 schools were targeted by these emails," police spokesperson Constantia Dimoglidou told AFP, adding that a similar hoax had been carried out in Cyprus.
"The computer server was spotted in Russia," she added.
In a statement, the police said the stunt was aimed at "disrupting public order".
Some of the establishments concerned were evacuated and the students had to return home, school officials and parents of students also told AFP.
One school director, who did not want to be named, said the email was titled "there are explosive devices in the school".
The message referred to the jihadist attacks in Paris on November 13, 2015, and said: "we are going to blow you up like our brothers did in Paris."
Another part of the email, threatening to "burn your stadium", was deemed an apparent reference to the Europa Conference League final in Athens on Wednesday.
In early May, Slovak police opened an anti-terrorism investigation after 1,100 bomb threats were sent by email to schools and banks across the country.