(Recasts with vaccine order)

CANBERRA, May 26 (Reuters) - Australia's government ordered 10 million doses of swine flu vaccine being developed by pharmaceutical company CSL Ltd CSL.AX on Thursday as the number of confirmed H1N1 cases in Australia topped 100.

Health Minister Nicola Roxon said the government would also buy a further 1.6 million courses of antiviral drug Relenza to bolster the national stockpile to 10.3 million courses of anti-viral drugs.

“We are working very hard to contain this,” Roxon told reporters in Canberra, where she confirmed the number of H1N1 cases had climbed from 61 on Wednesday to 103 by Thursday.

Most cases were in Australia’s most populous states of New South Wales and Victoria in the country’s south east, which are heading into the southern winter and regular flu season.

Of the confirmed cases, three are on a cruise liner, the Pacific Dawn, which will now return to a major port rather than continue with its planned voyage north to the state of Queensland.

Roxon said CSL expects its H1N1 vaccine to be ready within a few months, with the company planning to start clinical trials to make sure the vaccine is safe and effective for human use.

The supply would cover just less than half of Australia’s 21 million people, but Roxon said medical authorities would priorities which areas and people would most need the vaccine.

The government has also approved the first release of anti-viral drugs from the national stockpile, with 7,500 doses of paediatric Tamiflu to be relased in the Victoria and Western Australia states, and 10,000 packets of Tamiflu to Victoria.

“These localised releases from the stockpile will enable aggressive containment of small clusters of the disease,” Roxon said.