Newly diagnosed cases of chlamydia leapt 17 per cent to 74,305 in 2010, while those for gonorrhoea rose 25 per cent to just exceed 10,000.
There were substantially higher rates for both STIs among Aborigines and Torres Strait Islanders.
Indigenous people accounted for more than a third of all gonorrhoea cases and nine per cent of chlamydia cases.
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The figures featured in the latest surveillance report on HIV, viral hepatitis and sexually transmitted infections (STIs) released on Tuesday by the University of NSW's Kirby Institute.
The institute's Associate Professor David Wilson said the rise in gonorrhoea and chlamydia cases was partly due to more people being tested in response to public education campaigns.
"However, what we are seeing right now is the rate of diagnosis is surpassing the rate of testing, so that indicates there's an increase in overall infection levels," he said.
"So there's an epidemic.
"Almost 75,000 people were diagnosed with chlamydia last year.
"That's phenomenal. That's more than any other country."
Chlamydia and gonorrhoea can affect women and men who have sex with an infected partner.
Both STIs are treatable with antibiotics, but they can be hard to diagnose because infected people often show no symptoms.
If left untreated in women, the infections can lead to pelvic inflammatory disease (PID), which is the main cause of infertility.
Assoc Prof Wilson attributed the rise in the number of chlamydia and gonorrhoea cases to men failing to practice safe sex by using condoms.
Young heterosexual people were the most likely to be infected with chlamydia, the most common STI in Australia, while men who have sex with men were the most likely to have gonorrhoea.
Young people aged 15 to 29 accounted for 80 per cent of the total cases of chlamydia diagnosed during the year.
The increase in cases among women was almost quadruple the rise seen in 2009, while men showed a more than threefold increase.
Meanwhile, HIV and viral hepatitis remained at fairly stable levels in 2010.
The number of new HIV diagnoses was 1043, pushing the total number of cases recorded in Australia above 30,000 for the first time.
Australian Federation of AIDS Organisations executive director Rob Lake said while Australia had done well to contain the number of new HIV cases to about 1000 a year, it was time to "move beyond this plateau and decrease infection rates".
He said Australia had committed to a United Nations goal of halving new HIV infection rates before 2015 and one of the best ways of achieving that would be by introducing rapid HIV testing.
"Overseas experience has shown that when rapid (an initial result within an hour) HIV testing is offered, testing rates increase, and many people who have never previously tested present for testing," Mr Lake said.
