The arrests come amid concern among human rights groups and activists over the state’s growing intolerance towards the lesbian, gay, bisexual and transgender (LGBT) community in Malaysia in recent years.

Same-sex acts are illegal in Malaysia, although convictions are rare. The country has a dual-track legal system, with Islamic criminal and family laws applicable to Muslims running alongside civil laws.

Twenty people were arrested for offences under sharia, or Islamic law, during a raid on an event in Kuala Lumpur on Saturday, district police said in a statement.

Numan Afifi, an LGBT rights activist who was among those arrested, said they were accused of violating Islamic laws on cross-dressing, encouraging vice, and indecent acts in public places.

“They (authorities) isolated the Muslim participants, and identified anyone that did not dress according to the gender that they thought them to be,” Numan told Reuters.

“But of course it’s Halloween, people were dressing in costumes, so not all of them were cross-dressing.”

Eighteen of those arrested were questioned by religious officers on Monday before being asked to return for further enquiries at a later date, Numan said.

“It’s outrageous state oppression,” he said.

The Federal Territories Islamic Religious Department did not immediately respond to a request for comment.

Opposition lawmaker Charles Santiago condemned the arrests, describing the raid as harassment of a marginalised community.

“These targeted persecution against the LGBTQ+ community has the potential to trigger hate crimes… I urge authorities to cease hunting them down as if they are criminals,” he said in a Twitter post.

The New York-based Human Rights Watch said in a 71-page report in August that government officials had fostered a hostile climate in Malaysia through use of criminal penalties and programmes aiming to “cure” LGBT people.