Nigeria’s health minister has warned that bisexual men pose a “challenge” to efforts to tackle the spread of HIV in the country, as the prevalence of HIV among gay and bisexual men in the country was found to have risen.

Onyebuchi Chukwu, launching the 2010 Integrated Biological and Behavioural Surveillance in Abuja, said that HIV prevalence among men who have sex with men has risen to 17.2%, up from 13.5% in 2007, Nigeria’s Daily Trust reports.

But the report says half of the surveyed men who have sex with men also said they have sexual contact with women.

Chukwu said the link between the groups of men who have sex with men and the female population “poses a challenge to the national response to HIV epidemic.”

“If care is not taken, this behaviour may erode the gains we have made in the national response to HIV/AIDS.”

The survey studied some 14,987 people classified in high-risk groups—including female sex workers, men who have sex with men, police and armed forces personnel, transport workers and injecting drug users.

It found the prevalence of HIV among female sex-workers and the armed forces had fallen over the three year period.

Earlier this month, 60,000 people signed a petition calling on the Nigerian president not to increase the penalties for homosexuality, which is illegal in the African country.

Campaigners said the bill, which has been passed by the Senate, further criminalises any public relationship between two people of the same gender by classifying it as a “same-sex marriage”, for which it introduces a punishment of 14 years’ imprisonment.