The Thai king has signed same-sex marriage into law, the official Royal Gazette said Tuesday, making Thailand the first country in Southeast Asia to recognize marriage equality.

King Maha Vajiralongkorn gave royal assent to the new law, passed by parliament in June, which will take effect in 120 days — meaning the first weddings are expected to take place in January.

Activists hailed a "monumental step" as Thailand becomes only the third place in Asia where same-sex couples can tie the knot, after Taiwan and Nepal.

The law on marriage now uses gender-neutral terms in place of "men", "women", "husbands" and "wives", and also grants adoption and inheritance rights to same-sex couples.

The king's formal approval marks the culmination of years of campaigning and thwarted attempts to pass equal marriage laws.

"The law is a monumental step towards equal rights in Thailand," Waaddao Chumaporn, an LGBTQ rights advocate, told AFP.

She plans to organize a mass wedding for more than a thousand LGBTQ couples in Bangkok on January 22, the first day the law takes effect.

"We are all delighted and excited. We've been fighting for our rights for over 10 years, and now it's finally happening," Siritata Ninlapruek, an LGBTQ activist, told AFP, her voice shaking.

Prime Minister Paetongtarn Shinawatra posted congratulations "for everyone's love" on social media platform X.

"Thank you for the support from all sectors. It is a joint fight for everyone," she wrote with the "lovewins" hashtag.

Thailand has long had an international reputation for tolerance of the LGBTQ community, and opinion polls reported in local media have shown overwhelming public support for equal marriage.

However, much of the Buddhist-majority kingdom retains traditional and conservative values and LGBTQ people say they still face barriers and discrimination in everyday life.

More than 30 countries around the world have legalized marriage for all since the Netherlands became the first to celebrate same-sex unions in 2001.

India's highest court deferred a decision on the matter to parliament last year and Hong Kong's top court stopped just short of granting full marriage rights.

Long struggle

Thai activists have been pushing for same-sex marriage rights for more than a decade, with their advocacy stalled by political turbulence in a country regularly upended by coups and mass street protests.

LGBTQ activists staged a drag show in Bangkok on Friday to celebrate progress and show their enthusiasm for the law to come into effect.

Apiwat Apiwatsayree, a well-known figure in Thailand's LGBTQ community, and his partner Sappanyoo Panatkool, are among those who have been waiting for the law to pass so they can finally marry.

"We've been waiting for a long time," said Apiwat, 49, having been together for 17 years.

"As soon as it becomes law, we will go register our marriage," he told AFP on Friday.

The legislation was pushed through parliament by then prime minister Srettha Thavisin, who was vocal in his support for the LGBTQ community.

He made marriage equality a signature issue and told reporters last year that he believed the change would strengthen family structures.

"Another important step for Thailand. The same-sex marriage law passes. Equality is concrete here in Thailand," Srettha posted on X.

Srettha was kicked out of office by a court order in an ethics case in August and replaced by Paetongtarn, the daughter of controversial ex-premier Thaksin Shinawatra.

by Thanaporn Promyamyai and Montira Rungjirajittranon, AFP