A Finnish member of parliament has been found guilty by the country’s supreme court of inciting hatred after claiming that homosexuality was a “developmental disorder”, in a conviction that prompted criticism from far-right government ministers.

Päivi Räsänen, of the Christian Democrats, made the claims in a pamphlet first published in 2004 and reproduced on the website of the Luther Foundation Finland and the Finnish Evangelical Mission Diocese in 2007.

In a 3-2 vote, the supreme court on Thursday found Räsänen guilty of a crime when she republished the pamphlet on Facebook in 2019 and on her website the following year. She was fined €1,800. The court ruled her claim that homosexuality was a disorder of psychosexual development was incorrect.

Räsänen was supported in her case by the US-based conservative legal advocacy group Alliance Defending Freedom, which has tried to use her case as an example of censorship in Europe. The group has ramped up its global spending on litigation and other campaigns after successfully overturning Roe v Wade, which protected the right to abortion, in the US.

Räsänen said the outcome was “a shock” and that she would consider appealing against the ruling at the European court of human rights. Lower courts had acquitted her of all charges.

Finnish government ministers from Räsänen’s party and the nationalist Finns party immediately called for freedom of speech and legislative changes.

The verdict has elicited strong reactions from Räsänen’s party and top politicians including the minister of justice, Leena Meri, who called for a change in the law.

The Finns party had, she said, long believed that the law was “not sufficiently precise and especially not predictable as required by the principle of legality in the criminal code”, she said.

“It is very difficult for people to know what is prohibited and what is permitted.”

The deputy prime minister and minister of finance, Riikka Purra, also from the Finns party, also called for a change in the law. “Freedom of speech took another serious hit today through the supreme court’s voting decision,” she said on social media.

The prosecutor general, Ari-Pekka Koivisto, told Finnish broadcaster Yle: “We have not had a preliminary decision of this kind related to the crime of incitement before.”

Koivisto added: “It is significant because the supreme court went through the fundamental rights assessment in detail.”

But the prime minister, Petteri Orpo, of the National Coalition party, declined to take a position on the supreme court’s decision, saying politicians should not comment on court decisions.