Health authorities in Australia's far north are concerned about what they're calling an HIV cluster among men who work in Papua New Guinea.Six men have recently been diagnosed with the virus in Cairns and authorities say it could be the beginning of a large outbreak.

Authorities are warning men travelling to Papua New Guinea to practice safe sex after the recent spate of dignosies of HIV among men travelling there to work. Area Health Service Co-ordinator for the Cairns Sexual health service Cathy O'Mullan says they were alarmed by the outbreak.

"In 2007 for example 20 per cent of all the new HIV diagnosies in Cairns were acquired by heterosexual males who'd actually reported sexual contact in Papua New Guinea so that's quite an unusual and dramatic increase, previously during 2006 only six per cent were reported among that target group," she said.The State government plans to launch an education campaign among men travelling to PNG in November.