The United Nations programme for HIV and AIDS says more needs to be done to overcome infections in Papua New Guinea.
PNG is one of only four countries in the Asia-Pacific region to have seen an increase in new infections this year.
The country director for UNAIDS, David Bridger, said this came amid a drop in support from donors.
He said recent research conducted in Port Moresby, Mt Hagen and Lae showed that prevalence was extremely high among key populations, such as men who have sex with men and prostitutes.
Mr Bridger said this was an indication that much more needed to be done, especially since many of those infected had not been tested before.
"As soon as people know their HIV status we need to be doing a lot more to support them, to get them onto treatment and keep them on treatment," Mr Bridger said.
"Because one of the things that we have learned in the last year, certainly, is that unfortunately PNG has probably the second highest level of drug resistance in the world."
Mr Bridger said methods of preventing the spread of HIV also needed better promotion in PNG.