(Recasts, adds comment from Ugandan gay community spokesman and background)
KAMPALA, Feb 24 (Reuters) - Ugandan President Yoweri Museveni will sign an anti-homosexuality bill into law on Monday, the government said, defying protests from Western donors and U.S. President Barack Obama.
The new law will punish people convicted of having gay sex with jail terms up to life, according to drafts of the legislation. The final bill has not been published.
It will also make it a crime to promote gay activity - and to fail to report someone for breaking the new law, again according to drafts.
"The president is signing the anti-homosexuality bill today," Ugandan Government spokesman Ofwono Opondo told Reuters.
"He wants to sign it with the full witness of the international media to demonstrate Uganda's independence in the face of Western pressure and provocation," Opondo said.
Homosexuality is taboo in almost all African countries and illegal in 37 - including Uganda where rights groups say gay people already risk jail. Few Africans are openly gay, as they fear violence, imprisonment and loss of their jobs.
Gay and lesbian organisations in Africa fear the ripple effect from the anti-gay bill could spread beyond Uganda to other parts of a continent where conservative societies tend to view homosexuality as unnatural.
"It's a gloomy day not just for the gay community in Uganda but for all Ugandans who care about human rights because this law will affect everybody," said Julian Peppe Onziema, spokesman for the Lesbian, Gay, Bisexual, Transgender and Intersex (LGBTI) community in Uganda.
Harassment of people suspected of being gay has increased since the parliament passed the bill in December, Onziema told Reuters.
Donors have threatened to cut aid if the bill goes into law and U.S. President Barack Obama on Feb. 16 warned it would complicate relations with Washington, calling it "step backward for all Ugandans".
But while African leaders broadly court Western donors with promises to tackle human rights abuses, many have taken a hardline stance against homosexuality, describing it a "un-African" behaviour.
The anti-gay bill was introduced in 2009 and initially proposed a death sentence for homosexual acts, but was amended after an international outcry.
Museveni's decision to sign the bill comes less than a week since he announced plans to put the bill on hold to give scientists a chance to prove that homosexuality could be triggered by genes and was not a "lifestyle choice".
Uganda is a key Western ally in the fight against Islamic extremism in Somalia where Ugandan troops have formed the backbone of the African Union peacekeeping force battling al Qaeda-aligned militants. (Reporting by Elias Biryabarema; Writing by Drazen Jorgic; Editing by Eric Walsh)