(CNN) Brunei's new law punishing homosexual sex with death by stoning has sent a wave of fear across the LGBT population in neighboring Malaysia and Indonesia.

On April 3, the small oil-rich kingdom of Brunei introduced a strict Islamic legal code mandating death for adultery and sex between men, as well as lashes for lesbian sex and amputation for crimes like theft.

It has sparked a tide of condemnation from Western nations and celebrities alike. UN High Commissioner on Human Rights Michelle Bachelet on April 1 described the laws as "draconian" and a setback for human rights.

But across Brunei's border in Indonesia and Malaysia, both Muslim-majority countries, there has been official silence.

The lack of response from the prominent Southeast Asian leaders is likely to fuel concerns about the rise of conservative Islam in the region and the consequences for sexual and religious minorities.

Menag @lukmansaifuddin terima kunjungan Dubes Luar Biasa & Berkuasa Penuh RI untuk Bandar Seri Begawan Dr. Sujatmiko, MA. Keduanya membincang potensi kerjasama bilateral antara Indonesia dan Brunei Darussalam dalam bidang Keagamaan. pic.twitter.com/xB0c6ljMze — Kementerian Agama RI (@Kemenag_RI) April 1, 2019

In recent years, conservative Muslim groups have become a powerful force in the region, pushing for closer adherence to the more rigid of Islamic values and intimidating national governments.

Malaysian LGBT rights campaigner Thilaga Sulathireh said the immediate reaction among the gay community was concern the crackdown could spread.

"All these things are creating a lot of fear for people and a lot of uncertainty," she said. "What's going to happen to our lives and our future?"

CNN reached out to both the Indonesian and Malaysian governments for comment.

Rise of conservative Islam

Brunei is the first country in Southeast Asia to impose capital punishment for crimes such as LGBT sex or adultery, but neighboring Malaysia and Indonesia have been experimenting with strict Islamic laws for years.

Malaysia already enforces a mixed secular and religious legal system, with some regions mandating Sharia laws punishing what the penal code calls "unnatural" acts such as homosexual sex with caning and fines, while Indonesia's conservative northwestern province of Aceh has a history of enacting Sharia law.

Human Rights Watch researcher Andreas Harsono said Brunei public prosecutors even visited Aceh in 2014, ahead of the introduction of Sharia law in their own country, to learn about its implementation.

Conservative politicians in Indonesia and Malaysia voiced their support for the Brunei laws this month. One member of Parliament from the Pan-Malaysian Islamic Party congratulated Brunei Sultan Hassanal Bolkiah on his "bravery."

"Congratulations to Brunei for their bravery and political will in implementing Sharia criminal law ... upholding the Sharia is an obligation in ensuring Allah's rights to maintain peace for humans," Mohd Khairuddin Aman Razali wrote on his official Facebook page.

In Indonesia, one of the leaders of the legislative Ulama Council in Aceh told local news media that Brunei's laws were just "religious freedom."

Harsono said he was concerned that already vocal conservative Muslims in Malaysia and Indonesia would use Brunei's example to strengthen calls for stricter Islamic policies and laws.

"Already there are more than 60 local regencies and three provinces with mandatory hijab regulations in Indonesia. More than 20 local areas have regulations criminalizing LGBT people," he said.

As of Friday, there had been no official comment on the laws from either Indonesian President Joko Widodo or Malaysian Prime Minister Mahathir Mohamad.

Harsono said he did not expect Widodo, who is running for reelection, to speak until he knew how prominent Indonesian Islamic organizations would respond. "If the NU is opposed to hand amputation, Jokowi will speak up indeed," he said, referring to the Nahdlatul Ulama mass religious movement.

"If they don't, Jokowi will not risk his election on making such a statement."

Indonesia's President Joko Widodo (C), who is running for his second term, and his running mate, Islamic cleric Ma'ruf Amin (3rd L) in September.

Moving backward

Neither Indonesia nor Malaysia has national laws similar to Brunei's. In Malaysia, homosexual sex is illegal but punished by prison sentences. In Indonesia, it is still legal but culturally taboo.

But both countries in recent years have seen a steady rise in powerful conservative Islamic groups, who have pressed for tougher legislation in line with religious morality.

"It's impossible now for any politician to take a stance on religious matters without consulting their Muslim advisers and supporters," Harsono said.

Ahead of the April 17 Indonesian election, Widodo controversially picked conservative Islamic scholar Ma'ruf Amin as his candidate for vice-president.

In 2017, local media quoted Ma'ruf as saying he regretted the Constitutional Court's decision to reject a petition criminalizing gay sex.

"We want a stern prohibition of LGBT activities and other deviant sexual activities and legislation that categorizes them as crime," he told reporters in 2016.

Indonesian Muslim demonstrators, holding banners that read "put Ahok in jail," march towards the presidential palace in Jakarta on November 4, 2016.

Indonesia's minister for religious affairs met with the Brunei ambassador just days after the news of Brunei's law broke, but publicly only mentioned halal certification and religious education. There was no mention of the Sharia law.

Conservative Islamic groups helped rally popular support for the imprisonment in 2017 of Widodo's former ally, Jakarta mayor and Christian Basuki "Ahok" Tjahaja Purnama, on what some saw as trumped-up blasphemy charges.

Activists said the rise of conservative Islamic groups had been marked by growing homophobia in both countries, and an increase in official action against LGBT people.

In September 2018 two women were publicly caned in the Malaysian state of Terengganu for the first time for attempting to have sex in a parked car. One month earlier, one of Kuala Lumpur's only gay clubs was raided.

Malaysian LGBT rights campaigner Sulathireh said when some rainbow flags appeared at an International Women's Day march earlier this year, there was a pronounced backlash against attendees.

"It resulted in people at the rally being questioned by their family members, their employers, their schools, about why they were there," she said.

Observers gather to witness the caning of two women convicted of having sex in Terengganu, Malaysia, in 2018.

'Anything is possible'

The idea that Indonesia or Malaysia might move to impose stricter Islamic laws isn't just theoretical. There have already been clear attempts by anti-LGBT activists.

In early 2018, a large coalition of conservative Muslim groups presented a case to the Indonesian Constitutional Court to introduce a new penal code criminalizing LGBT relations.

The move was eventually abandoned, but the groups that supported it are still a powerful force in the country.

It was this law that actor George Clooney alluded to in an opinion piece for "Deadline," in which he warned about the potential fallout from Brunei's decision and called for a boycott of major hotels owned by the sultanate.

"The most dangerous issue is Brunei's neighbors. Indonesia has plenty of human rights issues, but they haven't stoned anyone yet," the actor wrote.

"But there was a law on the books, and if Brunei isn't met with loud, forceful resistance that shakes their business establishments, then anything is possible."