Dozens of gay men are reported to have been arrested across northern Nigeria as police begin to enforce punitive new laws that criminalise same-sex marriages and membership of gay rights organisations.
The legislation, condemned by US Secretary of State John Kerry and human rights groups, has come into force just after the Ugandan parliament also passed an anti-homosexual law.
Last week Nigerian President Goodluck Jonathan signed the Same Sex Marriage Prohibition Act, which provides penalties of up to 14 years in jail for a gay marriage and up to 10 years' imprisonment for membership or encouragement of gay clubs, societies and organisations.
Spokesman Reuben Abati said: "This law is in line with the people's cultural and religious inclination. So it is a law that is a reflection of the beliefs and orientation of Nigerian people ... Nigerians are pleased with it."
Dorothy Aken'Ova, executive director of the country's International Centre for Reproductive Health and Sexual Rights, said the legislation, hailed the "Jail the Gays" law, had led to mass arrests. She said police in Bauchi state had a list of 168 purportedly gay men, of whom 38 had been arrested. Aken'Ova warned that the laws would endanger medical programmes combating HIV/Aids in the gay community. Nigeria has the second-largest HIV epidemic, with an estimated 3.4 million people living with the virus.
Responding to the spread of anti-gay legislation, Kerry said: "The United States is deeply concerned by Nigeria's enactment of the Same Sex Marriage Prohibition Act. Beyond even prohibiting same-sex marriage, this law dangerously restricts freedom of assembly, association and expression for all Nigerians.
"[The law] is inconsistent with Nigeria's international legal obligations and undermines the democratic reforms and human rights protections enshrined in its 1999 constitution.
"People everywhere deserve to live in freedom and equality. No one should face violence or discrimination for who they are or who they love."
The London-based Human Dignity Trust, which supports legal actions around the world aimed at overturning anti-gay legislation, criticised both the Nigerian and Ugandan acts.
Trust chief executive Jonathan Cooper has described the Ugandan legislation as "a bleak day for human rights". "The bill undermines Uganda's human rights protection, breaches its international treaty obligations and violates Uganda's own constitution," he said.
One of the men whose legal challenges the trust supported, Roger Jean-Claude Mbede, 34, died this week after being removed from hospital by his family. He had been jailed in Cameroon for sending a text message to another man saying: "I'm very much in love with you."
Mbede, whose case was highlighted by The Guardian in 2012, was subsequently declared a prisoner of conscience by Amnesty International. His lawyer, Alice Nkom, said: "His family said he was a curse for them and that we should let him die."
Shawn Gaylord of Human Rights First, a Washington-based organisation, said he was alarmed by reports of torture and arrests in Nigeria.
"When discriminatory bills like this are passed, we are always concerned that they set the stage for violence and ill-treatment in society even when they are not enforced," he said. "But the fact that this law is being enforced so quickly and forcefully demonstrates the full extent of Nigeria's human rights crisis."
Additional reporting by Associated Press