At least 300 schools in Italy were evacuated on Wednesday after receiving the same bomb alert message, the education minister said.
The security alert came amid rising concerns in Europe about so-called hybrid warfare threats which have targeted supermarkets, blood banks, air traffic and TV broadcasters.
Education Minister Giuseppe Valditara told the La7 TV channel that the alerts were presumed to be hoaxes, adding that the number of schools affected was expected to rise.