Fire rages in the treeline near sports fields at Waitaki Boy's High School last week. PHOTO: NIC DUFF

Two 13-year-old boys have been referred to Youth Aid after a huge fire engulfed trees at Waitaki Boys’ High School in Oamaru, police say.

Last week’s fire was being treated as suspicious by police, who had identified "several individuals" to be spoken to as part of inquiries.

Sergeant Tony Woodbridge, of Oamaru, said today that two 13-year-old boys had been referred to Youth Aid for "their part in the large fire".

Sgt Woodbridge said he could not comment further on the fire’s cause.

The school avoided structural damage after the fire tore through about 200m of trees along the end of the school’s Don Field on Tuesday last week.

A Fire and Emergency New Zealand spokesman said crews responded to a call just before 9am.

Four fire trucks were on the scene and all firefighters were wearing breathing apparatus.

Waitaki Boys' High School rector Darryl Paterson said two boys had been suspended from school following the fire.

He said last week he was relieved no-one was hurt and that there was "no major damage" to any major school assets, in particular the caretaker’s house, which was "very close to the fire".

Students were evacuated from class just after 9am following the school’s fire drill procedure, he said.

 - Allied Media