[WORST HIT: Victoria's new alert level means the state can more intensely target those at risk of contracting the virus. PICTURE: AFP]

AUSTRALIA'S Influenza A (H1N1) flu outbreak topped 620 yesterday - making it the biggest outside Mexico, US and Canada.

There was just one case a fortnight ago, reported AFP.

Hardest hit has been Victoria state, which includes Melbourne.

The state yesterday officially abandoned its attempts to contain the H1N1 virus as its diagnoses jumped by almost a third to 521.

It upgraded its alert status from 'contain' to 'sustain' in response to the growing number of infections acquired locally rather than through international travel, reported the Australian.

Victoria's new alert level means the state can more intensely target those at risk of contracting the virus.

Health Minister Nicola Roxon said this would involve testing people in vulnerable settings such as aged-care facilities, hospitals and special schools and implementing more extensive tracing of those at risk of severe complications from the bug, reported Xinhua.

Ms Roxon said: 'I've been advised by the chief medical officer that it's appropriate to move Victoria to a modified 'sustain' phase,' she said.

'I've provided that advice to the prime minister, who has agreed that is the appropriate action to take. The rest of the country will remain at 'contain'.'

Three states, NSW, Queensland and South Australia, yesterday ordered children who had travelled to Melbourne to stay away from schools for a week on their return.

Tasmania and the Northern Territory also warned they would apply the same public scrutiny to people with flu-like symptoms coming from Victoria as given to travellers from Mexico and the US.

Ms Roxon yesterday predicted the Victorian scenario could be repeated in other states and territories, which currently remain in the 'contain' pandemic alert phase.

'It's inevitable that other states and territories will move to this phase over time. We are putting effort into delaying that for as long as we can,' she said.

Meanwhile, Commonwealth Chief Medical Officer Jim Bishop announced random flu testing would begin around the country in a bid to understand how the virus was spreading.

Australia has recorded no deaths from swine flu despite its rising infection rate.

The World Health Organization (WHO) said on Tuesday that it was moving closer to declaring swine flu a worldwide pandemic.

The disease has reached 66 countries.

19,273 infected

So far, 19,273 people are known to have been infected since the disease was first uncovered in April, data from WHO showed.

To raise the flu alert to its highest level, Level 6, WHO would need to find evidence of widespread 'community transmission' - meaning beyond travellers, schools and immediate contacts - on two continents.

Dr Keiji Fukuda, the agency's chief of flu, said that finding had not been made, reported The New York Times.

The agency is debating new rules for assessing global disease outbreaks. If it declares a Level 6 pandemic, Dr Fukuda said, it may add a caveat indicating that the virus is not very lethal. The flu has been blamed for only 117 deaths.

Meanwhile some airlines have decided to implement new measures.

Cathay Pacific now replaces used pillows, blankets, headset covers and headrest covers, spokeswoman Carolyn Leung said.

China Southern Airlines has been disinfecting the cabins of all aircraft. China Eastern Airlines flight attendants are required to wear disposable facial masks, gloves and hats.

Singapore Airlines, the world's biggest by market value, is giving passengers travelling to the US health kits that include a thermometer, masks and antiseptic towels, reported Reuters. Its cabin and flight crews are getting mandatory temperature checks before flights.

This article was first published in The New Paper.