"The Schools Inspectorate has criticised... Andreas Gymnasium for not having followed the statutory requirements with regard to the school's fundamental values and work to prevent and hinder students from being subjected to degrading treatment," the inspectorate wrote in its decision.
The inspectorate furthermore adds that the incident is particularly serious as the school has been criticised before for not taking measures to protect students from harassment.
Andreas Gymnasium, a school for students aged 16-19-years-old located in Solna, was reported to the Schools Inspectorate by a student in February 2010.
The report contained allegations that teachers at the school had on several occasions presented homosexuality as a sin, a view upheld by the school's principal at the time during an assembly.
"Most of the school's students are in agreement with the principal that homosexual acts are sinful and those who don't think the same risk being frozen out," the student wrote in the report.
"Something has to be done against the prevailing attitudes towards homosexuality shown by certain teachers and students," the student argued.
The school's current principal, Therése Wallén, who was appointed after the incidents described in the report, told The Local on Wednesday that the school has accepted the inspectorate's criticism and plans to address the situation.
"We have to work harder to develop our equal treatment plan," she said.
Many of the incidents described by the student occurred during discussions specifically concerning how to address the school's value-system covering issues such as race, gender and sexuality.
As a basis for the discussion a reading was made of texts from the bible. The student argued that the verses were interpreted by the principal to present her view that homosexuality is a sin.
Therése Wallén explained that while the bible is used in religious teaching at the school, she argued that it is not used as a basis for other teaching.
"It is true that the then principal gave the bible's view on homosexuality. I think it was wrong that it was used on this occasion and that no further discussion was held," she said.
The Schools Inspectorate noted that the school had declined to deny the student's claims that members of its staff have forwarded views linking homosexuality and sin.
When asked by the The Local for her opinion as a representative of the school on the issue, Thérese Wallén replied:
"We don't think it is the school's role to express a view on the issue. We follow the law and treat all people equally regardless of sexuality."
The Schools Inspectorate has reminded the school of its responsibilities according to existing legislation and has called on them to submit a report on measures adopted to address the complaints by July 2011.
Andreas Gymnasium was previously criticised in 2007 by the Schools Inspectorate with regards to the deficient development of its value-system.
The school has also received media attention in the past after a former principal told Sveriges Television that its teaching provides for students for learn alternatives to the theory of evolution, such as creationism and "intelligent design".