Documents in the possession of the Mail & Guardian show that the Ugandan ministerial task team asked by the president to advise him on homosexuality falsified the information contained in the report given by medical and psychological experts, twisting it to show that homosexuality should indeed be further criminalised.

The law, which Uganda's Parliament passed in December 2013, proposes severe penalties for same-sex romantic and sexual behaviour.

Under international pressure, President Yoweri Museveni delayed signing the controversial Bill into law, asking for a panel of experts to be convened to advise on whether homosexuality was "learned" behaviour or an inborn condition.

The experts – including academics from Marekere University and officials in the Ugandan ministry of health – said that, in their view and in terms of the best current medical knowledge, "homosexuality has no clear-cut cause", though they adduce some limited genetic evidence, and that "several factors are involved which differ from individual to individual. It is not a disease that has a treatment."

The Scientist Consensus Statement concludes that homosexuality is not a disease or an "abnormality", but that it "can be influenced by environmental factors" such as "culture, religion, information, permissiveness". Homosexual behaviour, the statement says, "needs regulation like any other human behaviour, especially to protect the vulnerable", and concludes: "There is need for studies to address sexualities in the African context."

By contrast, in the report to the president in the name of the caucus of the ruling National Resistance Movement (NRM), this is glossed as: "Homosexuality is not a disease but merely an abnormal behaviour which may be learned through experiences in life." It quotes the experts saying that the "practice should be regulated", following that with the statement: "Presidential Advisor on Science Dr Richard Tushemereirwe stated that homosexuality has serious Public Health consequences and should therefore not be tolerated."

Tushemereirwe was not part of the 10-member scientists' panel.

'Victory for Uganda'

The Bill was first mooted in Uganda in 2009, when it proposed the death penalty for homosexual activities. A global outcry followed, with objections raised then and later by African rights groups and Western politicians and donors, but MPs finally pushed the Bill through Parliament in December.

MP David Bahati, the Bill's sponsor, said it was a "victory for Uganda" and for African tradition against Western influences. But the anti-gay thrust of the Bill has also been driven by Christian evangelical groups working in Uganda. Gay activists from Uganda sued American missionary Scott Lively, under the "alien torts" law, for spreading homophobia in Africa. Other African countries such as Nigeria have recently passed anti-gay laws.

The new law, which awaits Museveni's signature, updates a colonial-era law regulating "carnal knowledge against the order of nature". It extends the penalty of life imprisonment for actual gay sex to all behaviour, including touching, that might lead to or show an intention to have homosexual sex: it penalises "any erotic behaviour intended to cause sexual excitement or any indecent act or behaviour tending to corrupt morals".

Earlier this year, in a letter to a Ugandan newspaper, Museveni wrote: "You cannot call an abnormality an alternative orientation. It could be that the Western societies, on account of random breeding, have generated many abnormal people." He added that he thought others might become gay for "mercenary reasons" or, in the case of lesbians, a lack of sex with men.

The law also makes it a crime, punishable by a prison term of up to seven years, for a citizen to fail to report homosexual activity to the authorities.

US President Barack Obama called the law "odious". Human Rights Watch has said it is "appalling", even without the death sentence. Amnesty International said the law "amounts to a grave assault on human rights".

The Ugandan Parliament also passed a law banning pornography and other forms of what it regards as sexual titillation, such as miniskirts.