Published: 2019-07-11 12:29:43 BdST
The human rights group said South Korea’s military code "does not comply with the international human rights obligations the state has signed on to".
"By institutionalising discrimination, laws criminalising sex between men reinforce systematic prejudices toward gay men, bisexual men, transgender people and non-binary people, whether in the military or in the street or in the home," Amnesty said in a report released on Thursday.
The South Korean ministry of defence did not immediately respond to a request for comment, but in the past South Korea has defended the code as necessary to maintain discipline.
The Amnesty report comes as South Korea engages in a broader debate over the future of its conscript military force - with recent court rulings clearing the way for conscientious objectors and political leaders promising to shorten service commitments - as well as controversy over changing social norms.
Amnesty urged South Korea to repeal Article 92-6 of the Military Criminal Act, which it said effectively prohibited and punished sex between men in the military.
"The military code in South Korea allows the invasion of privacy of soldiers alleged to be engaging in sex between men both on and off base, and on or off duty," the report concluded.
"Decriminalisation does not solve the entire issue, but it is a crucial first step towards respecting, protecting and fulfilling the human rights of LGBTI people."
Homosexual activity is not criminalised for South Korean civilians, but same-sex couples do not have the right to marry of adopt.
In March, the US-based Human Rights Watch (HRW) submitted an amicus brief in a challenge to the military code now before South Korea's Constitutional Court, alleging that the code "violates many norms of international law".
"South Korea’s military sodomy law is a blight on the country’s human rights record and multiple human rights bodies have called for its abolition," Graeme Reid, the LGBT rights director at HRW, said at the time.
A survey of South Koreans released in March by the Academy of Korean Studies found about 45 percent of respondents were comfortable working around gay people, while less than 16 percent said they would be comfortable with an gay person in their family.