At least 97 people who have been convicted of sex crimes ranging from rape to child pornography have jobs in Swedish schools, the Dagens Nyheter (DN) newspaper reported.
One example involved a man in his 50s who continues to work at a school in central Sweden despite having been convicted for buying sex from a minor he met online.
Another case involved a man in his 20s who works at a primary school in western Sweden despite having been convicted for sexually exploiting a child after forcing a 14-year-old old girl to have sex with him on repeated occasions.
The newspaper's investigation of criminal records of people who work at public schools in Sweden's 290 municipalities also found an additional 100 employees, including teachers, who are under suspicion for sex crimes but have yet to face trial.
As many of the sex offenders were employed at a school at the time they committed their crimes, they were not covered by legislation passed a decade ago that now requires potential employees to submit a criminal background check to schools or youth centres before they can be hired.
If a copy of an applicant's criminal record, obtained from the National Police Board (Rikspolisstyrelsen), reveals that he or she has been convicted of a sex crime, schools should "be very careful and thorough with other checks before a making a decision on employment", according to the Swedish National Agency for Education (Skolverket).
However, a loophole in the law allows people who remain employed at the same school they worked at when the committed their crimes to continue to hide their conviction from their employers.
In many cases, teachers have simply taken vacation during their trials, DN reported.
While medical professionals are covered by regulations that require courts to inform the National Board of Health and Welfare (Socialstyrelsen) when a doctor or nurse is convicted of serious crimes, there is no equivalent mechanism for schools in Sweden.
The Ombudsman for Children in Sweden (Barnombudsmannen) wants to see new legislation so that schools are informed when a teacher is convicted of a serious crime.
"There is a risk that these people can commit crimes again. It's very inappropriate that they are in this type of environment," ombudsman Fredrik Malmberg told DN.