Police on Thursday arrested and charged a 17-year-old boy with 74 separate offences over alleged bomb hoaxes made to educational facilities across Victoria, New South Wales and South Australia.

A joint operation of detectives across three states came together for the investigation into calls made between May 2016 and April 2017.

Last year teachers were forced to boost their emergency response strategies after a spree of threats to staff and students sent schools into lockdown on a regular basis.

Thousands of students were evacuated in one single day across Victoria and NSW after a co-ordinated hoax which involved multiple phone calls and computerised messages of a bomb in a backpack.

One automated call warned of a “bloodbath in 40 minutes” while in another phone conversation a man warned a Melbourne school receptionist she did not have long to live.

Less than a week later more than 20 schools were evacuated after another wave of calls threatening shootings and bombings.

STUDENTS EVACUATED OR FACE LOCKDOWNS AFTER THREATS ACROSS VICTORIA, NSW AND ABROAD

MUMS SPEAK OF PETRIFYING DASH TO VICTORIAN SCHOOL GATES AFTER HOAX THREAT

VICTORIANS BOOST EMERGENCY DRILLS AS HOAX CALLS CONTINUE

It is unknown whether the charges laid against the 17-year-old relate to these specifics threats or to other alleged hoax calls made over the past 12 months.

The youth appeared in Children’s Court of Victoria on Thursday afternoon and received bail to June 26.

He has received 74 charges spreading across three states including nine counts of make bomb hoax in Victoria, and 62 counts of use carriage service to make a hoax threat in NSW and South Australia.

Victoria Police’s senior media adviser Senior Sergeant Sharon Darcy said the E-Crime Squad regularly worked on lengthy operations with other agencies to tackle cyber threats made across the state.

“The states will continue to work together to investigate Cyber and High Tech crime and the teams are dedicated to reducing these types of incidents.”