A spokesman at a court in the central Tochigi region told AFP the three former and current teachers were found guilty of professional negligence resulting in injury and death.

The avalanche triggered by heavy snow killed seven high school students and a teacher during a three-day expedition to Tochigi's Mount Chausu in March 2017.

The disaster also injured 40 others on the mountain 120 kilometres (75 miles) north of Tokyo.

At issue throughout the trial was whether the avalanche could have been predicted.

The Utsunomiya District Court ruled on Thursday that it was "sufficiently foreseeable" and faulted the defendants for failing to do proper research, according to broadcaster TBS.

Prosecutors had argued that the amount of snowfall should have been a warning for the teachers, saying that the students could have been saved if better safety measures had been followed, several other media outlets reported.

The defence sought acquittals for the teachers by arguing that they had no way of predicting the snowslide.

In October 2017, a third-party panel tasked with probing the tragedy blamed it partly on complacency and a "lack of crisis-management awareness" among the supervisors.