Tokyo (CNN) More Japanese children and teenagers killed themselves between 2016 and 2017 than in any year since 1986, according to a new government report.

The latest survey shows 250 elementary and high school age children took their own lives in that year for a variety of reasons including bullying, family issues and stress, the country's Ministry of Education said Monday, according to local media.

Those figures were 5 up on the previous year, and the highest since 1986, when 268 pupils died.

"The number of suicides of students have stayed high, and that is an alarming issue which should be tackled," ministry official Noriaki Kitazaki told reporters. He said the cause of the rise was unclear.

Most of those who killed themselves were high school students. The government previously recorded an annual spike in suicides on September 1, the start of the new school year.