The European Commission is to launch legal action against EU member Hungary on Thursday in response to a law seen as discriminating against LGBTQ citizens.
A senior EU source told AFP that Brussels would send Prime Minister Viktor Orban's government a warning letter on Wednesday and begin the "infraction procedure" on Thursday.
Last week, European Commission president Ursula von der Leyen warned that the EU would use "all powers available" to force Hungary to repeal or modify the law.
The so-called "anti-paedophilia" law came into force on Thursday last week despite Brussels' warning.
The legislation was billed as a way to protect children but opponents argue that it conflates paedophilia with homosexuality and stigmatises the LGBTQ community.
Brussels' letter is the first step in a procedure that could lead to a case before the European Court of Justice and from there to financial penalties on Hungary.
Separately, the commission has also yet to approve Hungary's application for 7.2 billion euros in coronavirus recovery funding, even as other member states expect to receive their first payments.