High school pupils in Kråkstad and Skotbu were asked to take the letter home to their parents this week. In the letter, the children’s guardians were requested to contact the school to certify that they had read it, newspaper Østlandets Blad reports.

"The school has received notification from a reliable source that secondary school girls in secondary are selling sex to boys at school. The school does not have much knowledge of who is doing this or the extent to which it is happening,” principal Marit Rismyhr wrote.

The principal added that she and the school nurse planned to go around to each of the secondary school classes to inform them that the school was treating the matter as very serious and wanted it to stop immediately.

Many parents have reacted angrily to the school’s decision to send the letter, Østlandets Blad said.

“The school is making very serious allegations here against pupils aged from 12 or 13 to 16 who are under the age of sexual consent,” said one father, who asked not to be named, to the newspaper.

“It seems that the type of sexual activity, the number of pupils involved, and the extent to which it is happening have not yet been established. Is it really necessary then to direct suspicions against all of the pupils with this kind of letter?”

Local police said they intended to speak to the school to find out more about the allegations.