Gay activists on Tuesday vowed to fight the Nigerian government after the country outlawed same-sex unions, warning the act legitimised homophobic violence and increased fears of persecution.
President Goodluck Jonathan signed the Same Sex Marriage (Prohibition) Bill 2013 into law earlier this month, his spokesman Reuben Abati said on Monday, saying it reflected the majority view.
The law, which could see anyone who enters into a same-sex marriage or civil partnership jailed for up to 14 years, effectively reinforces existing legislation on the statute books banning homosexuality.
Jonathan's promulgation of the law barely registered a mention in Nigeria's newspapers.
There was wide support for the move on social media, however.
One contributor to BBC World Service radio's "World Have Your Say" Twitter feed said that "over 99.9% of Nigerians wanted this ban, same-sex is strange to us, it can't be accepted".
Nigeria is a highly religious country, with evangelicalism popular in the Christian-majority south, while the north is mainly Muslim and Islamic law runs alongside state and federal justice systems.
Research published in June last year by Pew Research Global Attitudes Project suggested that 98 percent of Nigerians thought homosexuality should not be accepted by society.
But the law has spread fear among Nigeria's lesbian, gay, bisexual and transgender (LGBT) community and disappointment among their supporters abroad.
One gay man in Lagos, whom AFP did not identify in case of reprisals, said he was "devastated" by Jonathan's actions and "terrified" at the consequences.
"I am concerned especially for LGBT people up north, in the (southern) Niger Delta... and for LGBT people in the whole of the country actually," he added.
"They (the government) have just legalised violence, stigma and discrimination.... Our situation has gone from bad to worse."
In London, LGBT activist and human rights campaigner Davis Mac-Iyalla said the legislation would force the community deeper underground.
But it also created a climate of suspicion and could affect access to services.
Fear and suspicion
Included in the law is a provision to punish with a jail term of up to 10 years anyone who registers, operates or participates in gay clubs, societies and organisations.
Anyone who directly or indirectly makes a public show of a same-sex relationship will also break the law and could face jail.
Mac-Iyalla said sympathetic health professionals may now be reluctant to provide treatment for conditions such as HIV for fear of prosecution.
Landlords and other tenants could also point the finger at same-sex tenants, even if they were just friends, he added.
"The worst part of it is that there are existing laws that have criminalised same sex relationships. I don't know anyone (in Nigeria) who's asking for same-sex marriage," he said.
"The general context is the further punishment and criminalisation of homosexuality."
Mac-Iyalla said he believed there was room to challenge the legislation through Nigeria's courts, despite its apparent widespread acceptance.
"I still believe there are lawyers and people from the human rights angle would be interested in taking this case.
"Human rights can be fought from anywhere, nationally or internationally.
"We're not going to keep quiet and accept such a draconian law."
The US Secretary of State, John Kerry, led international condemnation of Nigeria, saying it was "deeply concerned" about the law, which follows similar legislation proposed in Uganda.
Amnesty International and gay rights activists and groups have also condemned the law, calling it discriminatory and incompatible with international human rights laws to which Nigeria is a signatory.
In all, homosexuality is illegal in 78 countries worldwide and punishable by death in seven, according to the UNAIDS organisation.
"It (the law) is a licence to violence," said the gay Nigerian man spoken to by AFP.
"In this country we have people being lynched because of their sexual orientation and gender identity...
"I am afraid for people who can't even speak for themselves and who are going to end up in jail without anyone knowing about it."