Ugandan police have raided the offices of a United States-funded project known to offer AIDS services to homosexuals, a government spokesman said.
The crackdown appeared to be the first public action by police to enforce a new law that has strengthened criminal penalties against gay sex.
The Makerere University Walter Reed Project in the Ugandan capital of Kampala was targeted for "training youths in homosexuality," spokesman Ofwono Opondo said on Twitter on Friday. He offered no further details but said a "top diplomat" was involved in the alleged training.
Frank Mugisha, a gay leader in Uganda, said a Ugandan who worked for the project had been arrested and interrogated by police on Thursday.
The project - a nonprofit partnership between a Ugandan university and the US Military HIV Research Program - was known to offer services to gays who suffer from AIDS, he said.
"A lot of LGBTI people found it comfortable to go there for anti-retroviral treatment," he said.
Patrick Onyango, a spokesman for Ugandan police, denied the raid, saying a man pretending to represent the police threatened workers at the project, which has since been closed by administrators.
Onyango said police were now looking for the man, after police in his jurisdiction briefly arrested him and then freed him.
"Yesterday somebody claiming to be a police officer went and arrested one of the workers there," Onyango said. "Today the management of [the project] has decided to close the place. We are not investigating that place at all.''
Daniel Travis, a spokesman for the US Embassy in Kampala, declined to comment.
Uganda's president in February enacted a new measure that allows up to life imprisonment for those convicted of engaging in gay sex and sets a seven-year jail term for the offence of "attempted homosexuality."
Despite criticism from the US and other Western countries that say the law is draconian and should be repealed, it has wide popularity among Ugandans.
On Monday it became the first legislation in Uganda to be publicly celebrated in a rally attended by Ugandan President Yoweri Museveni, who told a raucous crowd that he was "mobilizing" to fight Western gays he accuses of promoting homosexuality in Africa.
At that rally, attended by thousands of Ugandans, Museveni said gays deserved to be punished severely because homosexuality is "criminal and it is so cruel."