The state prosecutor is to take the case of Åke Green, a pentacostalist pastor who in January was found not guilty of spreading hatred against homosexuals, to the Supreme Court.
Last year Green was sentenced to one month in prison under a controversial Swedish law that forbids agitation against certain minorities, including homosexuals.
In a sermon delivered in 2003 the pastor said that homosexuality is a "cancer on the face of society", and said that it could lead to bestiality and paedophilia. The details came to the attention of the prosecutor when Green himself distributed the text of the sermon to the local media in Borgholm, on the island of Öland.
In the original verdict, the court ruled that certain phrases in his sermon amounted to an attempt to stir up hatred of homosexuals.
But in January the appeal court in Jönköping overturned the verdict, finding "no evidence that the pastor was using his preaching as a cover to attack homosexuals". Green was freed, a decision which gay rights groups described as "disturbing".
On Wednesday morning the state prosecutor, Fredrik Wersälls, announced his decision to appeal against the not guilty verdict.
"In the sermon there were statements which must be interpreted as extremely offensive for homosexuals," said the prosecutor in a press release.
"We need guiding pronouncements about where the boundaries lie between an objective, genuine discussion and punishable abuse, as well as what the significance is if the person making the offensive statements says he has support for them in religious documents."
The Supreme Court has not yet indicated whether it will hear the case but a case which squarely pits the rights of minority groups against the right to free speech is unlikely to be ignored.
Sören Andersson, chairman of RFSL, the Swedish gay rights movement, said he supported the decision of the state prosecutor, despite the fact that "many writers maintain that freedom of expression and religions freedom mean that to make statements as Green did should be permissible".
"As far as we're concerned, it can never be part of freedom of expression to spread hatred against homosexuals and bisexuals as Green did," said Andersson.
"Religious places should not be a free zone for agitation against minority groups, and not just on the grounds of sexual orientation," he added.
Speaking to Dagens Nyheter, even Åke Green himself said that he sees advantages in the case reaching Sweden's Supreme Court.
"A decision in the highest court is influential to a higher degree than an appeal court verdict. If I am found not guilty in the Supreme Court it will send a strong signal to the legal profession and the rest of society," said Green.
The pastor confirmed that if, on the contrary, he was found guilty again, he would take the case to the European Court of Human Rights.
"Yes, my lawyer and I are completely willing to take it there if the Supreme Court finds me guilty of agitation against homosexuals. It would put another focus altogether on the issues I took up in my sermon. There are advantages to such an outcome."