JAKARTA, Indonesia >> Police in Indonesia have arrested 141 men at a sauna in the capital on suspicion of having a gay sex party, the latest crackdown on homosexuality in the country.

After the arrests in Jakarta on Sunday night, the police released to local news organizations numerous photographs of shirtless men who had been detained, alarming rights activists who said friends and families of the men may not have been aware of their sexual orientation.

Same-sex relations are not illegal in most of Indonesia, a predominantly Muslim nation, although gay people are frequent targets of police raids and vigilante actions.

A police spokesman said the men had been detained on suspicion of violating Indonesia’s pornography law, a broad piece of legislation that is used to punish a wide range of sexual behavior.

Similar police raids and arrests have been reported around the country, including in Jakarta in November, when 13 men were taken into custody after the police were tipped off about what was said to be a gay sex party. Last week, two men in the northwestern province of Aceh were sentenced under Shariah law to 85 public lashes each for having sex with each other.

Because of strong social and religious taboos against homosexuality in much of Indonesia, gatherings of gays often take place away from the public eye, like in saunas or at underground parties.

“It’s very difficult for us to express our sexuality like heterosexuals,” said Hartoyo, the director of Suara Kita, a gay rights advocacy group, who goes by one name. He said that releasing pictures of the shirtless men to local news outlets was “extremely dangerous.”

Analysts said the arrests in Jakarta were part of enforcement efforts by the police before Ramadan, the monthlong holiday in which observant Muslims fast throughout the day.

Tobias Basuki, an analyst at the Center for Strategic and International Studies in Jakarta, said the police appeared to be formally taking on a role that had previously been held by hard-line Islamist groups.

“The government is trying to co-opt the religious narrative,” he said.

The Indonesian government, under the leadership of its pluralist president, Joko Widodo, has been engaged in political battles with hard-line Islamist factions that recently succeeded in getting a close presidential ally, Basuki Tjahaja Purnama, Jakarta’s Christian governor, imprisoned on blasphemy charges.

“We urge the government to overturn Mr. Purnama’s sentence on appeal or to extend to him whatever form of clemency may be available under Indonesian law, so that he may be released from prison immediately,” three independent U.N. experts said in a statement Monday.

Basuki (no relation to the former governor) said that one way for the government to resist hard-line Islamist groups was to take over the role of enforcing Islamic behavioral norms from vigilantes.

“The police are being seemingly more strict,” he said, “but they will allow less latitude towards vigilante groups.”

Jakarta’s government recently announced that most bars and nightclubs in the city would be closed during Ramadan, a departure from last year, when they were generally allowed to stay open. Over the past few weeks, the police destroyed 16,000 bottles of alcohol being sold by unlicensed vendors in pre-Ramadan raids, according to local news media.

“There’s a shift in the atmosphere of religiosity in Indonesia,” Basuki, the analyst, said.

The two young men discovered in bed together in Aceh, who were sentenced last week to caning, are expected to be punished Tuesday. Activists say they believe the punishment has been scheduled to take place before the start of Ramadan, which begins Saturday in Indonesia.

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