Confirmed cases of swine flu in Indonesia have nearly doubled, with the national total standing at 52, Health Minister Siti Fadilah Supari said on Thursday.

Three foreigners were among 24 new cases of (A)H1N1, which included a dozen confirmed human-to-human transmissions, Supari told reporters.

All the patients were being treated in hospitals in the capital Jakarta, the tourist island of Bali and Balikpapan city in East Kalimantan province, she said.

"Indonesia will keep screening at all airports for foreigners who have travelled to areas where (the virus) is endemic," she said.

"We haven't found any mixing yet of the H1N1 and H5N1 (bird flu) viruses."

The first cases of swine flu emerged in Indonesia in June after a British tourist and an Indonesian pilot tested positive.

Supari said earlier that she was particularly worried about Australian tourists who flock to the surf beaches of Bali island. More than 300,000 Australian holidaymakers visited the island last year.

Australia is the Asia-Pacific country worst-hit by swine flu with almost 4,000 cases, while Indonesia has been the country hit hardest by avian influenza, reporting 115 deaths since 2005.

There are fears a combination of swine flu and avian influenza could create a deadly and rapid-spreading new strain of the disease.