School principals are experiencing increased violence from students and parents.

An NZEI survey shows violence towards school leaders has increased by 70 per cent between 2016 and 2018.

Principals' Federation president, Whetu Cormick, told Kate Hawkesby children - and angry parents - often lash out.

"School leaders are 11 times, almost 12 times, more likely than the general population to be receiving violence and threats of violence."