The UN chief Ban Ki-moon has called on Uganda to repeal a tough new law imposing life terms on homosexuals, warning it could fan violence and impede responses to HIV and AIDS.
Mr Ban "urges the government to protect all persons from violence and discrimination," his spokesman said.
He added that Mr Ban "hopes that the law can be revised or repealed at the earliest opportunity".
The UN chief believes that life terms "could fuel prejudice as well as encourage harassment and violence against lesbian, gay, bisexual and transgender persons".
The statement added that "it may also obstruct effective responses to HIV/AIDS".
Ugandan President Yoweri Museveni signed off on the controversial law that will see homosexuals jailed for life, shrugging off warnings from key international allies and donors.
The signing of the law, which also outlaws the promotion of homosexuality and requires people to denounce gays, came despite fierce criticism from US President Barack Obama and a warning that ties between Uganda and the US would be damaged.
The UN secretary general's concerns were conveyed to Uganda's permanent representative to the United Nations in New York yesterday, Mr Ban's spokesman said.
Mr Ban's statement came as a Ugandan newspaper published a list of 200 people it accused of being gay.
The Red Pepper tabloid showed photographs of Ugandans it said were homosexual underneath an "Exposed!" headline, as well as reporting on lurid stories of alleged homosexual actions.
In 2011, prominent Ugandan gay rights campaigner David Kato was bludgeoned to death at his home after a different newspaper splashed photos, names and addresses of homosexuals in Uganda on its front page along with a yellow banner reading "Hang Them".
Prominent Ugandan gay activist Jacqueline Kasha posted photographs of the newspaper's front page on Twitter, warning that the "media witch hunt is back".
Homophobia is widespread in Uganda, where American-style evangelical Christianity is on the rise.
Gay men and women in the country face frequent harassment and threats of violence, and rights activists have reported cases of lesbians being subjected to "corrective" rapes.