Campaigners in South Korea have condemned an attempt by conservative MPs to remove homophobia and transphobia from a list of violations of an anti-discrimination law.

An amendment submitted this month by Ahn Sang-soo, a member of the main opposition Liberty Korea party, seeks to remove sexual minorities from groups protected by the law, sparking protests by rights groups and members of the LGBT community.

Ahn, who has the backing of about 40 MPs in the 300-member national assembly, said the inclusion of the words “sexual orientation” in the law “legally and actively protects and promotes homosexuality”, according to a report by Raphael Rashid, a Seoul-based freelance journalist.

Ahn said that in its current form, the law discriminates against those who oppose homosexuality on religious or other grounds – an apparent reference to South Korea’s influential Christian lobby.

His amendment claims that the national human rights commission of Korea act “adversely affects teenagers and young people before their gender identities are established”, and that “a number of health hazards in the world are occurring, such as the unprecedented surge of new cases of Aids infections”, according to Rashid.

Ahn’s proposed change also restricts the definition of “gender” to that which is assigned at birth and ignores the right for individuals to choose their gender identity, according to Amnesty International.

Amnesty said passage of Ahn’s amendment would mark a “shameful step backwards for human rights in South Korea” and leave LGBT people “exposed to discrimination in all aspects of their lives and make them easy targets for abuse, threats and possibly violence, with no recourse to legal protection”.

Suki Chung, Amnesty’s Asia-Pacific LGBT rights campaigner, said Ahn’s move was “clearly designed to prevent transgender, intersex and gender non-conforming people to live a life according to their identity”.

Amnesty urged MPs to reject the amendment and “uphold laws that keep all citizens equal and safe”.

Activists have protested outside the assembly building in Seoul and called for the pro-amendment MPs to resign.

Two lawmakers from President Moon Jae-in’s ruling Democratic party of Korea who initially signed the amendment have reportedly withdrawn their support.