Uganda’s president has signed into law a bill toughening penalties for gay people and criminalizing those who do not report them.

A government spokesman said President Yoweri Museveni wanted to assert Uganda’s “independence in the face of Western pressure”.

The new law punishes first-time offenders with 14 years in jail, and allows life imprisonment as the penalty for acts of “aggravated homosexuality”. It also makes it a crime not to report gay people – in effect making it impossible to live as openly gay.

It criminalizes the “promotion” and even the mere “recognition” of homosexual relations “through or with the support of any government entity in Uganda or any other non-governmental organization inside or outside the country”.

Lesbians are covered by the bill for the first time.

Gay activists say they will challenge the new laws in court.

The bill originally proposed the death penalty for some homosexual acts, but that was later removed amid international criticism.

According to the Associated Press news agency, government officials clapped after Mr Museveni signed the bill at a press conference at State House.

Earlier government spokesman spokesman Ofwono Opondo told Reuters news agency Mr Museveni wanted “to demonstrate Uganda’s independence in the face of Western pressure and provocation”.

The sponsor of the bill, MP David Bahati, insisted homosexuality was a “behaviour that can be learned and can be unlearned”.

“Homosexuality is just bad behaviour, that should not be allowed in our society,” he said.

But a gay rights activist in Uganda said that he was “very scared” about the new bill.

“I didn’t even go to work today [Monday]. I’m locked up in the house.

“And I don’t know what’s going to happen now. I’m talking to all my activists on the phone. And it’s the same, they are all locked up in their houses. They can’t move out. They are watching their back to see what happens.”

The signing of the bill is an apparent U-turn from a recent pledge to hold off, pending advice from the US.

In a statement, Mr Museveni had said: “I… encourage the US government to help us by working with our scientists to study whether, indeed, there are people who are born homosexual.

“When that is proved, we can review this legislation.”

President Obama described it as “more than an affront, and a danger to, Uganda’s gay community. It will be a step backwards for all Ugandans.”

He warned it could “complicate” Washington’s relations with Uganda, which receives a reported $400m (£240m) in annual aid from the US.

In South Africa, former archbishop Desmond Tutu said he was disheartened by President Museveni’s apparent change of stance.