Nigerian legislators started hearings this week on a bill that would criminalise same-sex marriage and could make it punishable by five years in jail.

On Monday the senate opened debate on the bill proposed by a national assembly committee. The body is expected to vote on it in the next couple of weeks.

Africa's most populous nation is the latest on the continent seeking to tighten up laws against homosexuality, angering human rights groups and leading Western countries like Britain to threaten a withdrawal of foreign aid.

(A) marriage contract entered between persons of the same gender is hereby prohibited in Nigeria, reads a version of the bill published on the senate website.

Any persons or group that witnesses ... that aids the solemnisation of a same sex marriage contract commits an offence and is liable to a term of 5 years imprisonment ..

Under existing federal law, sodomy is punishable by jail, although in some northern states practising Islamic Sharia law it carries the death sentence.

According to the senate website, one version of the bill would outlaw any coming together of persons of same sex with the purpose of living together as husband and wife or for other purposes of same sexual relationship.

Two similar bills have been proposed since 2006 but failed to pass before the expiry of the parliamentary term.

Nigerian gays, who are often too terrified of persecution to speak out publicly, voiced opposition at the senate hearing.

A society that stifles sexual and other identities discourages the recognition of human dignity. LGBTI rights are human rights, said Otibho Obiowu, a representative of the Nigerian Lesbian, Gays, Bisexual, Transsexuals and Intersexual (LGBTI) association.

As in much of sub-Saharan Africa, anti-gay sentiment is rife in Nigeria, so the new legislation may be popular.

If we accept that two consenting adults can marry, we will soon ... have to ... argue whether mother and son, father and daughter are not free to marry, Michael Ekpenyong, secretary general of the Catholic Secretariat of Nigeria said in Monday's hearing.

Senate President David Mark voiced support for the bill.

My faith as Christian abhors it. It is incomprehensible to contemplate same sex marriage. I cannot understand it. I cannot be a party to it, he told the hearing, deriding what he called the importation of a foreign culture.

Threats by British Prime Minister David Cameron to cut aid to African countries that do not respect gay rights have sparked outrage in aid-dependent Uganda and Malawi.

In August, Uganda's cabinet blocked an attempt by some legislators to reintroduce a bill that called for the death penalty for some gays, mindful of the risk of foreign aid cuts.

But Nigeria, whose treasury is fed by its 2 million barrel-per-day oil production, can afford to overlook such threats.

Human rights Uganda Malawi Aids