Four gay couples have asked India's Supreme Court to recognise same-sex marriages, setting the stage for a legal face-off with Prime Minister Narendra Modi's government which has in the past refused to legalise such marriages.

In a historic verdict in 2018, India's top court decriminalised homosexuality by scrapping a colonial-era ban on gay sex. Despite the 2018 ruling, members of India's lesbian, gay, bisexual and transgender (LGBT) community complain about a lack of acceptance and discrimination against gay people in Indian society.

LGBT activists say that while 2018 ruling affirmed their constitutional rights, they are still deprived of legal backing for same-sex marriages, a basic right enjoyed by heterosexual married couples.

In three Supreme Court filings seen by Reuters, the couples say that without legal recognition of being married, they are denied rights such as those linked to medical consent, pensions, adoption or even simpler things like club memberships for couples.

Lawyers and a court listing confirmed a fourth petition along similar lines was also admitted by the court.

"We can't do so many things in the process of living together and building a life together,” said one of the litigants, businessman Uday Raj Anand, who wants to marry his partner Parth Mehrotra, chief editor of India's Juggernaut Books.

Another couple, Supriyo Chakraborty and Abhay Dang, say in their submission that they held a two-day commitment ceremony last year like any other “Big Fat Indian wedding”, but once the euphoria faded, they realised they could not take health insurance as couples or nominate each other in life insurance policies.

"”In truth, they have no rights at all,” the filing states.

The four gay couples want a Supreme Court ruling that modifies or interprets laws in a way that allows same-gender marriages, the court filings show. It is a sensitive subject in the socially conservative country of 1.4 billion people, where speaking openly about homosexuality is taboo for many.

The pleas have already triggered a debate on prime-time TV news and generated editorials in newspapers whether the time has come for the world's largest democracy to join roughly three dozen countries where such marriages are legal.

The United States this month approved legislation that provides federal recognition to same-sex marriages in a bid to further safeguard gay rights.

The Indian Supreme Court cases, which follow many lawsuits filed in lower courts where no decision was reached, will be a key test for Modi's Hindu nationalist government and his allies.

His law ministry has opposed same-sex marriages in the past and said courts should stay away from the law-making process that falls under parliament's purview.

In one state court filing last year, the law ministry said a marriage depends on“age-old customs (and) rituals” and a sexual relationship between same-sex individuals is “not comparable with the Indian family unit concept of a husband, a wife and children.”

It added that in India marriage is “a solemn institution between a biological man and a biological woman”.

Three spokespersons for Modi's ruling Bharatiya Janata Party, who declined to be named as the matter is before courts, said the party's opposition to same-sex marriage remains the same as the government's. They however added the party will honour the top court's verdict on the matter.

Modi's office and the federal law ministry did not respond to a request for comment whether there has been a change in their position on same-sex marriage.

The Supreme Court has given the government until Jan. 6 to submit its responses.

"With the top court taking up the case, the issue of marriage equality is likely to be decided at a hastened pace,” said Jayna Kothari, a gender-law expert who co-founded India's Centre for Law & Policy Research.

"A decision on same-sex marriage in the near future is inevitable. That will be a landmark moment.” Backing the couples are high-profile lawyers including one of India's former Attorney Generals and another counsel named Saurabh Kirpal, who is openly gay and in an interview last month accused Modi's government of delaying his elevation as a state judge due to his sexual orientation.

Kirpal and Modi's office did not respond to a request for comment on those remarks.