Out of 600 high school students who participated in a survey by the Svenska Dagbladet newspaper, 20 said they have had a sexual or romantic relationship with a teacher, with one percent claiming they are still in such a relationship.
Two percent said they have classmates who are in a sexual relationship with a teacher.
Five per cent, or 32 students, know or have heard of students in other classes or schools who are in relationships with teachers.
Around 80 percent of Swedes attend high school (gymnasium), which is not compulsory and corresponds to grades 10 to 12.
The law says that someone who persuades another person to engage in a sexual act by seriously taking advantage of that person's position of dependency should face up to two years in prison. However, the deed must constitute a clear abuse of power.
"The law could be better and clearer," said Kristina Huldt, a lawyer with experience of handling sexual abuse cases.
"As it stands, evidence is required that the teacher in question persuaded the pupil. That can be hard to prove," said Huldt.
For Gisele Priebe, a psychologist and researcher at Lund University, the problem is not whether sexual relations between teachers and pupils are illegal or not.
"Even if the pupil and teacher are in love 'for real' and there is no pressure involved, it is still a question of power imbalance. It is very hard, if not impossible, in these instances to have a relationship where both people's wishes and opinions count as much."
The Swedish National Agency for Education (Skolverket) did not want to comment on Svenska Dagbladet's findings.
"We have no direct views on this. The National Agency for Education does not have a position on this issue… This is a political issue," said Eva Röyter, a lawyer at the Agency.
The Teachers' Ethical Council (Lärarnas yrkesetiska råd), which is tasked with encouraging a continuing debate on work ethics and with promoting professional ethics among teachers, did not want to take a stand on the issue, either.
"You can't ban love. The fact that there is attraction is not strange, but we have to think about how we handle it," said Jesper Rehn of the Teachers' Ethical Council.
Rehn does not believe legislation is the way forward or that the Council should publish guidelines for how to deal with the issue.
Asked whose role it is to draw up such guidelines, Rehn replied: "That's a good question. I don't know."
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