Thousands of people are set to defy a government ban by participating in the Pride march in Budapest, Hungary's capital, on June 28.

Right-wing populist Viktor Orbans government and the Budapest police forbid the annual event under a new law that prohibits the exposure of young people to non-heterosexual lifestyles.

But Budapest mayor Gergely Karacsony, an opposition leader, has backed the event by co-organizing it with the city hall to declare it a municipal event, which wont require police approval.

Pride marches, a regular annual event in many Western cities, are occasions to highlight the rights of lesbian, gay, bisexual, transgender and queer (LGBTQ) people.

Orbans initiatives have been protested at home. The European Union and human rights groups have also condemned his actions.

"We're not just standing up for ourselves... If this law isn't overturned, eastern Europe could face a wave of similar measures," said Viktoria Radvanyi, an organizer of the march.

But on June 27, Orban warned the participants to be aware of "legal consequences". He said that the police would not break up the march.

Attendees can face fines of up to $580, while organizers can be imprisoned for up to a year. Authorities can use facial recognition technology to identify the participants.

Karacsony, however, has insisted that participants would not face any reprisals.

"The police have only one task tomorrow, and it is a serious one: to ensure the safety of Hungarian and European citizens attending the event," he said on June 27 during a briefing with visiting EU equalities commissioner Hadja Lahbib.

Bence Tuzson, the Hungarian justice minister, threatened Karacsony with a one-year prison sentence for helping to organize the event.

The minister has also warned foreign embassies in Budapest to inform them of the ban on the Pride march.

Some 35,000 people are expected to participate in the 30th edition of the Budapest Pride March. It is set to begin at 2:00 p.m. CET near Budapest's city hall.

Scores of European lawmakers and ministers from several EU countries are expected to attend the event to show solidarity with the participants.