Australians trapped in Wuhan are begging for help to get out, as China warned that people could be spreading the deadly illness before they had noticeable symptoms.

More than 100 Australians, many of them children aged between six months and 16 years, are in lockdown at the epicentre of the coronavirus outbreak.

The Department of Foreign Affairs and Trade is working closely with Chinese authorities to bring the children home, foreign Minister Marise Payne said in a statement to the ABC.

The four Australians with coronavirus did not show symptoms when they flew back to Australia, Australia's chief medical officer confirmed, and one of them did not report he was sick until nearly three weeks later.

As of Monday 12pm (AEDT), 80 people have died and more than 2744 have been infected, with four confirmed cases in Australia and others in countries including the USA, France, Thailand, Vietnam  and Canada.

“At present, the rate of development of the epidemic is accelerating,” Mr Ma said at a press conference.

“I am afraid that it will continue for some time, and the number of cases may increase.”

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Inset: Leo Yeung's family stayed in a hotel room for four days and were seeking help from Australian authorities. Photo: ABC

It comes as a fifth Australian case of a new coronavirus is expected to be confirmed on Monday as authorities work to track down people who have been in close contact with the person in recent weeks.

Swab testing of a 21-year-old Chinese woman from Sydney came back positive to 'probable' coronavirus, placing her in isolation in hospital until the results of further examinations were revealed.

Meanwhile, there fears the virus could be much more contagious than originally thought as it emerged that infected people could be spreading the virus for up to two weeks without even knowing, unlike Ebola and SARS victims who become contagious only once they develop symptoms.

China’s health minister Ma Xiaowei has revealed the virus can be contagious during the incubation period, which ranges from one to 14 days, making it much more difficult to identify potential victims early to  contain the spread.


Virus reaction

Hundreds of French citizens will be evacuated from the Wuhan area mid-week with the agreement of Chinese authorities.

Hong Kong has barred residents from Hubei province, the area at the centre of the coronavirus outbreak, from entering.

Meanwhile, anti-government protesters set alight the lobby of a new residential building in Hong Kong that authorities planned to use as a quarantine facility for the coronavirus outbreak.

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Inset: Riot police wearing facemasks gesture after residents set up barricades near the vacant Fai Ming Estate to protest against plans for the estate to be used as a quarantine camp for patients. Picture: Getty

In a desperate effort to curb further spread of the deadly virus, China imposed a national ban on the sale of all wildlife until the epidemic has been eliminated across the country.

It also withdrew as host of the qualifying tournament for the women's Olympic football at Tokyo 2020.

The event which was originally meant to be staged in Wuhan, where the coronavirus first broke out, has been moved to Sydney because of the "current situation" there.

Beijing has deployed more than 1600 doctors to Wuhan hospitals where there are significant shortages of medical supplies and personnel.
Australian cases of coronavirus

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Inset: Passengers from Wuhan arrived at Sydney International Airport on January 23. Photo: Getty

Three patients in NSW and one in Victoria have already been diagnosed with the virus after an outbreak centred in the Chinese city of Wuhan which has spread across the world.


Three men aged 35, 43, and 53 are being treated in a Sydney hospital but are listed as being stable and NSW Health Minister Brad Hazzard on Sunday said he was pleased with their progress.


Authorities have now spoken to all but two people who have been in close contact with the three men since they arrived from China.


"There are a small number of people we're still trying to contact but substantially we have made contact," NSW chief health officer Dr Kerry Chant said.


In Victoria, a man in his 50s is being treated at Monash Medical Centre while four of his family members are being quarantined at home.
A further 11 patients are now awaiting test results.


Queensland chief health officer Dr Jeannette Young said authorities were attempting to contact four people who may have come into contact with the Victorian patient after sharing the same flight.


"If these people are unwell, we will assess them for coronavirus," Dr Young said.


There have been zero reports of the virus in Queensland after six patients all tested negative on Sunday.


As health authorities work to track down local cases of coronavirus, the federal government is working with Chinese authorities to get Australians in affected areas home.


"Given the circumstances of the spread of the coronavirus, Chinese authorities are currently imposing very tight restrictions on all travel from Hubei," a statement from Foreign Minister Marise Payne read.

"We are seeking advice from the Chinese authorities on these restrictions and whether any options are available to international travellers."

-with AAP