Museveni himself last week referred to gay people as "these deviants".
Kampala
Amnesty International has urged Uganda's President Yoweri Museveni to reject a tough anti-gay bill passed by parliament, warning it was "a grave assault" on LGBTQ people.
Ugandan lawmakers on Tuesday evening hastily passed the bill ordering harsh penalties for anyone who engages in same-sex activity.
Homosexuality is already illegal in the conservative East African nation and it was not immediately clear what new penalties had been agreed.
"This ambiguous, vaguely worded law even criminalises those who 'promote' homosexuality," Amnesty's east and southern Africa director Tigere Chagutah said.
Lawmakers amended significant portions of the original draft legislation with all but one speaking in favour of the bill.
MP Fox Odoi-Oywelowo, a member of Museveni's National Resistance Movement, party who spoke against the bill, told AFP that offenders would face life imprisonment or even the death penalty for "aggravated" offences.
Amnesty said Museveni "must urgently veto this appalling legislation", adding that it would "institutionalise discrimination, hatred, and prejudice" against the LGBTQ community.
The discussion about the bill in parliament has been laced with homophobic language and Museveni himself last week referred to gay people as "these deviants".
Nevertheless, the 78-year-old leader has consistently signalled he does not view the issue as a priority, and would prefer to maintain good relations with Western donors and investors.
Uganda is notorious for its intolerance of homosexuality — which was criminalised under colonial-era laws.
But since independence from Britain in 1962 there has never been a conviction for consensual same-sex activity.
In 2014, Ugandan lawmakers passed a bill that called for life in prison for people caught having gay sex.
A court later struck down the law on a technicality, but it had already sparked international condemnation, with some Western nations freezing or redirecting millions of dollars of government aid in response.
Last week, police said they had arrested six men for "practising homosexuality" in the southern lakeside town of Jinja.
Another six men were arrested on the same charge on Sunday, according to police.