Same-sex couples in Thailand will be able to marry from next week, under Southeast Asia's first law allowing their unions. The Thai prime minister reaffirmed the country's commitment to promote diversity and gender equality.

Ninety LGBTQ couples gathered at the Government House on Wednesday for a celebration before the law takes effect on January 23.

The legislation has been one of the signature policies of the ruling Pheu Thai Party led by Prime Minister Paetongtarn Shinawatra.

She said, "From now on, no matter your gender, no matter who you love, there are no limits on love anymore. You'll be protected under the law just like any other couples."

The new law guarantees same-sex couples the same rights as those in heterosexual unions, including tax benefits, inheritance and adoption.

One participant said, "It's a big milestone for us, and for Thailand that we have this new law that comes into effect, that it's basically a legal acceptance of our love and of everyone's love. Anyone can love anyone."

A mass marriage registration event will take place in Bangkok next Thursday, with about 300 couples expected to tie the knot.