Hungary's ruling Fidesz party has proposed banning the "promotion" of sexuality of young people under a new law.
The bill would also outlaw promoting sex change among minors, including in schools, films or books.
The legal amendments were proposed by the conservative party of Prime Minister Viktor Orbán on Thursday, according to the parliament's website.
Five NGOs, including Amnesty International and Budapest Pride, immediately denounced the "new proposal" by Fidesz.
"Freedom of expression and children's rights would also be severely restricted," Amnesty Hungary said in a statement.
"This move endangers the mental health of LGBT+ youth and prevents them from accessing information and affirmative support in a timely, preventive manner."
"Such legislation only reinforces prejudice and homophobia, which is incompatible with the values of democratic societies," the organisation added.
The new law could see Hungary outlaw any advertisements by large groups or companies which stand in solidarity with the LGBT+ community.
In 2019, a #LoveIsLove campaign by Coca-Cola prompted calls for a boycott of the brand by members of the right-wing Fidesz party.
The legal amendments in Hungary seem to be the latest anti-LGBT move by Orban, who has defended traditional Christian values and claims homosexuality promotes a cultural "new era".
In December 2020, Hungary's Parliament adopted a legislative package enshrining the traditional notion of family and "gender" in the Constitution and effectively banned the adoption rights for same-sex couples.
A law passed last year also makes it impossible for citizens to have their changed gender registered in official documents.
Amnesty said that Hungary was following the model of legislation used in Russia and China, which punish acts of homosexual "propaganda".