A court in Burundi has charged 24 people for "homosexual practices" as authorities in the conservative East African nation crack down on same-sex relationships, a judicial source told AFP on Thursday.

Burundi has criminalised homosexuality since 2009 with a prison sentence of up to two years for consensual same-sex acts.

Police detained 17 men and seven women on February 23 at a seminar in the political capital Gitega being hosted by MUCO Burundi, a non-profit organisation that focuses on HIV/AIDS.

They were accused of promoting homosexuality and engaging in same-sex acts, both classed as crimes punishable with jail terms under Burundian law.

"After interrogations which lasted about ten days, the 24 were charged with homosexual practices and incitement to homosexual practices by the public prosecutor," Armel Niyongere, head of the human rights group ACAT Burundi, said late Wednesday.

They will be remanded in prison to await trial, said Niyongere, who has been living in exile in Belgium since 2014.

A judicial source in Burundi, who asked for anonymity to discuss the case, confirmed on Thursday the accused had been charged.

The 24 were arrested after neighbours alerted security officials to the alleged presence of teenage boys and girls at the MUCO office.

Police said that condoms were found on persons at the scene and the groups was arrested on suspicion of homosexuality.

Earlier this month, President Evariste Ndayishimiye urged citizens to root out homosexuality from the country.

"I ask all Burundians to curse those who indulge in homosexuality because God cannot bear it," he said in a speech.

"They must be banished, treated as pariahs in our country", he said.

Last month Burundian intelligence agents arrested five human rights activists, who were later charged with rebellion and undermining state security.