Malaysia's Islamic religious officers broke up a large Halloween party attended by the LGBT community and arrested 20 people for cross-dressing and allegedly encouraging vice, activists said on 30 October.

Activist Numan Afifi, who was among those arrested at the event in Kuala Lumpur late night on 29 October, described the raid as "traumatizing and harrowing."

"About 40 religious officers backed by the police came into the venue with some 1,000 participants, and they stopped the music and dance," he told AFP.

Numan said authorities divided partygoers into two groups — Muslims and followers of other faiths.

Subsequently, 20 Muslims were taken to the Federal Territories Islamic Religious Department where "our identity details were recorded."

All 20 were released a few hours later but are required to return next week for questioning.

The LGBT community has continuously suffered discrimination, with conservative attitudes chipping away at the Muslim-majority nation's one-time reputation for moderation and tolerance.

Malaysia has a dual-track legal system, with sharia courts handling some cases for Muslim citizens, who make up around 60 percent of the population.

Homosexuality is forbidden and laws criminalizing sodomy can result in imprisonment, corporal punishment and fines— although enforcement of the law is rare.

Siti Kassim, a human rights lawyer, condemned the raid, saying "moral policing must stop."

"These people are not criminals. The oppression and discrimination against LGBT people must end immediately," she told AFP.

Opposition politician Carles Santiago called the raid "harassment against a marginalized community."

"When will we learn to respect and accept people for who they are?" he tweeted.

Rights groups have on numerous occasions slammed Malaysian authorities for discrimination and coming up with programmes to "cure" LGBT people.

"These programmes jeopardize the equality, dignity, and rights of those who attend them, but also send a dangerous message to the wider public that LGBT people can and should change their sexual orientation, gender identity, and gender expression," Human Rights Watch said in August.