TAIPEI: Taiwan on Thursday proposed a draft law to allow same-sex marriage in Asia's first such bill, but the legislation was criticised by rights activists and conservative groups amid a heated debate over marriage equality.

Voters opposed marriage equality in a series of referendums late last year, defining marriage as between a man and a woman and asking for a special law to be enacted for same-sex unions.

The draft law unveiled by cabinet on Thursday would give same-sex couples similar legal protections for marriage as heterosexuals, but marriage in civil law would remain defined as between a man and woman.

Premier Su Tseng-chang said the bill respected the referendum results, although activists had said a separate law for gay marriage was discriminatory.

"Controversies are expected about the proposal, but I really hope our homosexual friends can wait a bit longer," Su said in a statement.

"This might fall short of expectations, but after all it's a start," he said.

Jennifer Lu, coordinator of Marriage Equality Coalition Taiwan, said the draft did not give complete legal protections to same-sex couples. She acknowledged the pressure on the government from all sides, but said activists will continue to fight for equal rights.

Taiwan's parliament is expected to vote on the draft bill by late May, a deadline for legislation set by the constitutional court in May 2017 when it ruled that same-sex couples had the right to legally marry.

The divisive issue has been a challenge for President Tsai Ing-wen, whose party suffered a major defeat in local elections in November amid criticism over her reform agenda, including marriage equality.

Conservative groups that opposed same-sex marriage during the referendum said they will fight the draft bill too. The Coalition for the Happiness of Our Next Generation on Thursday called the draft "unacceptable".