The measures were unveiled as the number of confirmed cases across the nation rose by around 25 percent. In the space of two weeks, Australia has gone from a single case to being the fourth hardest-hit country in the world.

The island state of Tasmania on Wednesday joined Queensland, New South Wales and South Australia by ordering that children arriving from Victoria be quarantined for up to seven days to reduce the threat of swine flu.

"The exclusion will apply for seven days from departure from Victoria," said Tasmania's Director of Public Health Chrissie Pickin.

"It applies to all children returning from Victoria and other affected areas, whether or not they have a flu-like illness," she said.

Victoria is the worst-hit state in Australia, with 521 confirmed cases, or four fifths of the nation's total. The number of confirmed cases in Australia rose on Thursday from 502 a day earlier.

Authorities raised the swine flu alert level in Victoria on Wednesday as patients flocked to emergency rooms.

As news reports compared Victoria with Mexico and the United States as a swine flu hotspot, the move by other states to blacklist travellers from Victoria raised the ire of the stricken state's health minister.

"At the end of the day, I think that decision will be rendered unworkable very, very soon as we see numbers grow in other states, and I would not say that that decision was proportionate with the risks posed by the H1N1 virus," said Victoria's Health Minister Daniel Andrews.

He said his government's moves to limit the spread of the disease were working, despite the large number of infections, most of them in schools.

"There is no doubt, and the experts have told us, that without the things already put in place, many, many more people -- much faster -- would have had H1N1," he said.

Swine flu has now spread to 66 countries with 19,273 people known to have been infected since the disease was first uncovered in April, the World Health Organization said Wednesday.