(CNN) -- Lawmakers in Uganda are preparing to vote on a new anti-homosexuality bill that proposes tough jail sentences for consensual same-sex behavior.
Homosexual acts are already illegal in the east African nation, where most gays and lesbians face physical attacks and are treated as social outcasts, but the new bill proposes harsher penalties.
Uganda's maximum penalty would be life in prison.
Amnesty International said it was "extremely concerned" about the bill and called on the Ugandan parliament not to pass it.
"The bill would have lasting, harmful effects on Ugandans who are thought to breach its far-reaching provisions and it would significantly hamper the work of human rights defenders and public health professionals," the rights group said.
"Although Amnesty International has been informed that some provisions of the bill have been amended, the content of these amendments have not been made publicly available.
"This bill violates the principle of nondiscrimination as guaranteed under international and regional treaties to which Uganda is a party."
"We are outraged," said Noel Kututwa, the rights group's director for southern Africa. "This goes beyond the principle of nondiscrimination. It goes against the principle of privacy of individuals. And sexual orientation is really a question of the right of an individual to choose how they want to live their lives."
Uganda's parliamentary speaker has reportedly said she wants the legislation to pass before Christmas.
World leaders condemned the anti-gay legislation when it was first proposed in 2009. Some nations have also threatened to withhold aid to Uganda over its record on same-sex rights.
Prominent gay rights activist David Kato was beaten to death in the country in 2011, a slaying that rights activists believe was motivated by homophobia.
A British producer was also briefly jailed in Uganda in September this year for staging without permission a play about the challenges facing homosexuals in the African nation.
If convicted, David Cecil could be imprisoned for two years, his lawyer said.
Homosexuality is illegal in most countries in Africa, where sodomy laws were introduced during colonialism.
The death penalty can be imposed in a handful of nations worldwide for consensual same-sex relations, including Nigeria, Sudan, Mauritania, Saudi Arabia and Iran, according to the International Lesbian, Gay, Bisexual, Trans and Intersex Association.
CNN's Victoria Eastwood contributed to this report.