Allowing gay couples to wed would “dilute and diminish” marriage and make it "no longer special", Hong Kong's government has argued in defence of its current ban.

Authorities in the former British colony are in the midst of a court battle over laws that prevent same-sex couples from entering into marital unions.

The case was brought by a woman known only as MK who said the ban on her entering a civil partnership with her girlfriend was unconstitutional.

Stewart Wong, a government lawyer, defended the existing law, saying: "Not all differences in treatment are unlawful. You are not supposed to treat unequal cases alike.

"To recognise an alternative form of same-sex relationships which we say is tantamount to [marriage] is to undermine the traditional institution of marriage and the family constituted by such a marriage."

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Hong Kong only decriminalised homosexuality in 1991 and does not recognise same-sex marriage or civil unions.

In January, two gay men launched separate legal bids to overturn the ban – the first such attempt to bring the autonomous territory in southeast China in line with the UK and much of Europe on the issue of equal marriage.

It came after Taiwan’s parliament passed a bill this month that endorsed same-sex marriage. More than 360 same-sex couples married last Friday.

Meanwhile in Hong Kong, authorities have become embroiled in a string of controversy's linked to the treatment of LGBT+ people in recent years.

Last July, 10 children’s books with LGBT+ themes – including one about two male penguins who hatch an egg and raise a youngster – were removed from the shelves of public libraries. Visitors instead needed to ask a librarian to access the books.

In the same month, the government lost a court battle over their refusal to issue a visa to a woman in a same-sex civil partnership.

And in May Hong Kong’s airport and transport system faced criticism after banning an advert featuring a same-sex couple.

The image, one in a series from airline Cathay Pacific’s new campaign, showed two men walking along a beach holding hands.

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The ban was later reversed by the territory’s Mass Automatic Railway(MTR) subway system and Hong Kong International Airport.

Amnesty International has previously warned that gay people in Hong Kong face "discrimination ... in all walks of life".