Banda Aceh, Indonesia: Rights activists called on Tuesday for Indonesia's Aceh province to release four people detained on suspicion of having homosexual sex, amid concerns over the persecution of the LGBT community in the world's third-largest democracy.

Secular Indonesia is predominantly Muslim but ultra-conservative Aceh is the only province to follow sharia, or Islamic law, and criminalise gay sex.

Indonesia's parliament is currently debating revisions to the national criminal code that could criminalise all sex outside marriage, including same-sex relations. Many believe the new rules could be used to unfairly target the LGBT community and other minority groups.

Authorities said the four suspects were rounded up by vigilantes and police and, if convicted, could face up to 100 lashes in public.

"We are completing their files and will soon hand over to prosecutors," said Marzuki, head of sharia police investigations in the provincial capital, Banda Aceh.

Human Rights Watch said the punishment "constitutes torture under international human rights law".

"Acehnese authorities should release the four and protect the public from marauding vigilantes who target vulnerable minorities," said Graeme Reid, director of the lesbian, gay, bisexual, and transgender (LGBT) rights programme at Human Rights Watch.

The provincial and central governments drew international condemnation last year when, for the first time, Aceh authorities publicly caned two men who were convicted under the province's anti-homosexuality laws, which were introduced in 2014.

Vigilantes and religious police in Aceh often raid homes and places of work and detain people on suspicion of engaging in homosexual activity.

Aceh police detained 12 transgender women earlier this year and publicly shamed them by forcing them to cut their hair and dress in "masculine" clothing.

They were later released without charge, but activists say many have since gone into hiding for fear of further raids.