Brunei's Sultan Hassanal Bolkiah (C) attends an event in Bandar Seri Begawan on April 3, 2019. Brunei's sultan called for Islamic teachings in the country to be strengthened as strict new sharia punishments, including death by stoning for gay sex and adultery, were due to come into force on April 3.

A growing list of multinational banks are banning employees from staying at hotels owned by the sultan of Brunei, where homosexuality and adultery is punishable by death.

J.P. Morgan, Goldman Sachs and others — called to task by celebrities such as Elton John, George Clooney and Ellen DeGeneres — have barred staff from staying at properties owned by the Dorchester Collection hotel group, run by the Brunei state-owned investment agency. The ban includes luxury names such as Los Angeles' Beverly Hills Hotel and Hotel Bel-Air, and London's Dorchester and 45 Park Lane.

The news was first reported by the Financial Times. A spokesperson for J.P. Morgan confirmed the report to CNBC but declined to comment further.

Deutsche Bank announced its boycott of Brunei-owned properties in early April as a sign of support for LGBTQ rights. Goldman Sachs and Bank of America have confirmed to CNBC that they are no longer using the Dorchester Group. CitiGroup, Jefferies, Morgan Stanley and Nomura have also banned employees from staying at nine luxury hotels owned by the small Southeast Asian nation, according to Financial News Network. Bank of New York Mellon joined the ban too, according to a spokesperson for the bank on Tuesday.

"The new laws introduced by Brunei breach the most basic human rights, and we believe it is our duty as a firm to take action against them," Stuart Lewis, chief risk officer and member of the management board at Deutsche Bank, said in a statement. "We are proud to support LGBTIQ rights around the world, and as part of this we regularly review our business partnerships to ensure that they are aligned with this principle."

Earlier this month, Brunei introduced laws that make gay sex punishable by death by stoning. Adultery, rape, sodomy, extramarital sexual relations for Muslims, robbery, and insult or defamation of the Prophet Muhammad are also banned — and prosecuted the same way. Homosexuality has always been illegal in the small, oil-rich nation, but the new, stricter Islamic laws introduce the death penalty as punishment.

In response to the boycotts, the Dorchester Collection said in a statement that they "understand people's anger and frustration but this is a political and religious issue that we don't believe should be played out in our hotels and amongst our 3,630 employees."

Singer Elton John and George Clooney have called for corporate boycotts. In a column published in Deadline last month, Clooney said, while you can't shame "murderous regimes," you can "shame the banks, the financiers and the institutions that do business with them and choose to look the other way."

The United Nations has also condemned the laws. U.N. High Commissioner for Human Rights Michelle Bachelet called them cruel and inhumane punishments that breach international human rights law. According to Amnesty International, gay sex is a crime in 72 countries and punishable by death in eight, including Saudi Arabia.

Still, in a recent interview Brunei's billionaire leader, Sultan Hassanal Bolkiah, who has an estimated $20 billion fortune, called for "stronger" Islamic teachings in the country, according to French news agency AFP. The sultan has been in power since 1967.

— CNBC's Ryan Ruggiero and Donovan Russo, and Holly Ellyatt contributed reporting.

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