(Wellington)  New Zealand's relatively good record of HIV/AIDS control took a knock Thursday with the publication of a study showing about a fifth of HIV-positive gay and bisexual men are unaware they are carrying the disease.

Tests on 1,049 gay and bisexual men in the country's largest city of Auckland found 67 of the men were carrying the virus, but 14 of them had no idea.

The study by the University of Otago was the first biological measure of HIV collected in community settings among Auckland's gay and bisexual men, providing an estimate of the amount of undiagnosed as well as overall HIV infection.

A statement from the university said the study was timely because in 2010 the highest number of new HIV diagnoses was recorded among gay and bisexual men in New Zealand, indicating that it remained a major health issue.

"The existence of people with undiagnosed HIV infection must be taken seriously if we're to bring HIV under better control," lead investigator Dr. Peter Saxton, of the university's Department of Preventive and Social Medicine, said in the statement.

"A person with undiagnosed HIV cannot tell someone they're infected and might not initiate safe sex. The practical reality of this is that everyone, especially gay men, needs to become better educated, supported and proficient at safe sex to control HIV and other sexually transmitted infections."

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