South Korea's Supreme Court recognized new rights for same-sex couples Thursday, saying the state must provide health insurance for a gay man's partner in a landmark ruling that left activists weeping for joy.

The country's highest court ruled it was "discrimination" for state health insurers to treat same-sex couples differently from their heterosexual counterparts, in a verdict that activists said could pave the way for the eventual legalisation of same-sex unions in the South.

"National Health Insurance should recognise spousal insurance coverage for same-sex couples," the court ruled, with activists breaking into cheers as the verdict was read out.

The verdict, which cannot be appealed, means common-law spouses of the same sex can now register as dependents on their partners' state health insurance -- something long permitted for heterosexual common-law partners.

The case was brought by a gay couple, So Seong-wook and Kim Yong-min, who live together and held a wedding ceremony in 2019.

It had no legal validity, however, as South Korea does not recognise same-sex marriage.

In 2021, So sued the National Health Insurance Service (NHIS) because it terminated benefits for his partner -- whom he had registered as a dependent -- after discovering they were a gay couple.

In a landmark ruling last year, a Seoul High Court found in favour of the couple, mandating that the NHIS reinstate the dependent benefits.

But the health service appealed the decision, escalating the case to the Supreme Court.

"Today, love won again," said So after the verdict.

His husband Kim struggled to hold back tears outside the courtroom, telling reporters that he had "always called (So) my husband, but he was never seen as my husband in Korea".

But today, "the court called So my same-sex partner and I am so happy for that to be recognised in court".

The Supreme Court ruled that it was "discrimination based on sexual orientation to exclude the couple just because they are same-sex".

The court ruled that the health service "decision to not recognize same-sex partners who have formed an economic community of life similar to a married couple as dependents... is unlawful".

The couple's lawyer Chang Suh-yeon said that the ruling "gives hope" to same-sex couples in South Korea, but said it did not go far enough.

"Guaranteeing simple rights is not considered complete equality and we will keep on fighting for same-sex marriage to be institutionalised," Chang told AFP.

'Historic victory'

The Supreme Court ruling is a pivotal moment for the country's LGBTQI community, and people holding rainbow umbrellas walked out of the court, wiping away tears of joy.

Ryu Min-hee, a lawyer and an LGBTQI activist, told AFP that "the ruling goes beyond just specific rights and benefits."

"It ultimately paves the way for the legalization of same-sex marriage in South Korea, following the lead of other Asian countries like Taiwan and Thailand," Ryu told AFP.

While South Korea does not recognise same-sex marriages, gay relationships are not criminalised. LGBTQ people tend to live largely under the radar.

Activists have long emphasised the need for legislation against discrimination on the basis of sexual orientation.

A much-discussed anti-discrimination law has languished in the South Korean parliament for years, due to a lack of consensus among MPs.

Outside the court ahead of the verdict, anti-LGBTQI Christian organisations staged a protest, holding up banners saying "let us repent to the Lord".

When the couple initially attempted to hold a press conference after the verdict, Christian activists disrupted it by speaking in tongues and shouting: "homosexuality is a sin!"

Amnesty International said the ruling was "a historic victory for equality and human rights in South Korea".

"The Court has taken a significant step towards dismantling systemic discrimination and ensuring inclusivity for all," the rights group said in a statement.

"While this decision is a major milestone, the case itself is a sobering reminder of the lengthy judicial processes that same-sex couples must endure to secure basic rights that should be universally guaranteed.

"It is disheartening that in 2024, same-sex couples still face such significant barriers to equality."