Brunei’s new Islamic criminal laws punishing gay sex and adultery by stoning offenders to death have triggered an outcry from countries, rights groups and celebrities far beyond the tiny south-east Asian nation’s shores.

The penalties were provided for under new sections of Brunei’s sharia penal code and took effect on Wednesday.

Celebrities including George Clooney, Elton John and Ellen DeGeneres have voiced opposition to the new laws, and have rallied a boycott of nine hotels in the US and Europe with ties to Brunei’s Sultan Hassanal Bolkiah.

“Let’s be clear, every single time we stay at or take meetings at or dine at any of these nine hotels we are putting money directly into the pockets of men who choose to stone and whip to death their own citizens for being gay or accused of adultery,” Clooney wrote in a guest column on Deadline Hollywood last week.

“Are we really going to help pay for these human rights violations? Are we really going to help fund the murder of innocent citizens?” the actor added.

Sultan Hassanal Bolkiah instituted the sharia penal code in 2014 to bolster the influence of Islam in the oil-rich monarchy of about 430,000 people, two-thirds of whom are Muslim.

But even before 2014, homosexuality was already punishable in the country by a jail term of up to 10 years.

The first stage of the sharia penal code included fines or jail for offenses such as pregnancy out of wedlock or failing to pray on Fridays. But under the new laws, those found guilty of gay sex can be stoned to death or whipped. Adulterers risk death by stoning too, while thieves face amputation of a right hand on their first offense and a left foot on their second. The laws also apply to children and foreigners, even if they are not Muslim.

“Living in Brunei, we already knew that our sexual identity is taboo and should not be expressed. We already felt belittled before the law came to place,” said a 23-year-old member of the LGBT community who wanted to be identified only as Kun out of fear of reprisal from the authorities.

“Now with it, we feel even smaller and the ones who could potentially oppress us have more opportunity to harass us to say and do what they want,” he said.

On Wednesday, customers at two prestigious Paris hotels owned by the sultan expressed their support for a boycott.

Outside the Le Meurice hotel, Philippe Menager said he was no longer comfortable going to the spa after being a regular customer for 15 years.

“I can’t continue to be a frequent visitor of the hotels of this savage to preserve the jobs of the people who work at Le Meurice – who are very nice and I like them,” he said.

A tourist from Norway, Anja Anderson, said she would have stayed at a hotel other than the Plaza Athenee had she heard about the boycott before making her reservation.

There has been no vocal opposition to the new penalties in Brunei, where the sultan rules as head of state with full executive authority. Public criticism of his policies is extremely rare in the country.

But outside of Brunei, opposition to the new laws has been fierce.

Phil Robertson, the deputy Asia director for Human Rights Watch, called on the sultan to “immediately suspend amputations, stoning, and all other rights-abusing provisions and punishments”.

“Brunei’s new penal code is barbaric to the core, imposing archaic punishments for acts that shouldn’t even be crimes,” Robertson said in a statement on Wednesday.

The United Nations said on Wednesday that the secretary-general, António Guterres, “stands clearly against any form of cruel punishment” and believes the Brunei legislation clearly violates the principles “that human rights are to be upheld in relations to every person everywhere without any kind of discrimination”.

“So long as people face criminalization, bias and violence based on their sexual orientation, gender identity or sex characteristics, we must redouble our efforts to end these violations,” said Guterres’ spokesman, Stephane Dujarric. “Everyone is entitled to live free and equal in dignity and rights.”

The United States has joined the United Kingdom, Germany and France in urging Brunei to halt its plans.

“The United States strongly opposes violence, criminalization and discrimination targeting vulnerable groups, including women at risk of violence, religious and ethnic minorities, and lesbian, gay, bisexual, transgender and intersex persons,” the state department deputy spokesman, Robert Palladino, said in a statement.

Brunei’s south-east Asian neighbors, some of whom have laws banning sex between men, were silent. But LGBT citizens of other nearby Muslim-majority countries were concerned about the broad penalties.

Nearly two-thirds of Malaysia’s 32 million people are Muslim. They are governed by Islamic courts in family, marriage and personal issues. Last year, two Malaysian Muslim women were convicted under Islamic laws and caned for attempting to have sex with each other.

Michelle Bachelet, the UN high commissioner for human rights, urged Brunei’s government to “stop the entry into force of this draconian new penal code”.

“Any religion-based legislation must not violate human rights, including the rights of those belonging to the majority religion as well as of religious minorities and non-believers,” she said in a statement.