France, already on its highest security alert, is to boost security at airports around the capital and on trains after a wave of bomb hoaxes, the transport minister said on Sunday.

Security patrols at Paris airports will be increased by 40% and staff at the national railway company SNCF will be reinforced by 20% in addition to extra police patrolling railway stations, minister Clement Beaune said on France Inter.

France has been on its highest alert since Oct. 13 after a 20-year-old man fatally stabbed a teacher in the city of Arras in northern France.

“Transport (networks) have been places that have seen heavy tolls in attacks in the history of our country and in Europe,” said Beaune.

Alongside the heightened risk, there were “people who are playing with fear”, he said, referring to the wave of fake bomb alerts that have hit transport networks, schools and cultural centres over the last week.