In a statement addressed to the approximately 20 Portuguese nationals living in the city, the Portuguese embassy in Beijing states that it had "immediately [begun] all the steps" to proceed with an airlift, using a chartered civilian aircraft "that will pick you up from Wuhan and from there take you directly to Portugal.

"This is the plan that is being weighed up in Lisbon and on which we are already asking for the due authorisations from the Chinese authorities in Beijing and Hubei” – the province of which Wuhan is the capital, the same statement continues.

Wuhan, in central China, was last week put under de facto quarantine, with arrivals and departures barred by the authorities for an indefinite period. The move caught most residents by surprise.

The government in Lisbon initially considered withdrawing its citizens by land, to Shanghai, in eastern China, from where they would be flown to Portugal.

However, such a plan would require permits from the provinces between Hubei from Shanghai, which would "take longer than expected to be obtained" and would require the Portuguese to be quarantined in one of these territories before they could leave China.

Italian news agency ANSA reported on Monday that Italy’s government is considering putting its citizens in Wuhan under quarantine in the neighbouring province of Hunan before getting them out to Italy.

Portugal’s government takes the view that this option "did not correspond to what we have always sought, which was direct evacuation to Portugal".

The government is also pondering carrying out the operation jointly with the evacuation efforts of other European Union member states, under the European solidarity mechanism provided for in this type of situation.

In the same statement, the government warns its nationals in Wuhan of the "possibility that upon arrival in Portugal, the Portuguese health authorities apply a quarantine period as a measure of prevention."

One Portuguese national living in Wuhan told Lusa that in what is China's seventh largest city, with 11 million inhabitants, the silence is "total", with "establishments closed and streets empty".

After the quarantine announcement by the authorities last Thursday, vegetables and other goods quickly sold out in the city's supermarkets as families accumulated supplies.

China today updated the death toll from the virus to 80, with more than 2,700 infected.

The public health emergency comes as China celebrates the Lunar New Year, the most important holiday of the Chinese calendar, equivalent to Christmas in western countries, and during which hundreds of millions of Chinese travel.

Beijing is considering extending the holidays and postponing the reopening of schools as part of efforts to contain the spread of the disease.

The virus was first discovered last month at a seafood market in the suburbs of Wuhan, which is a major domestic and international transport hub.

The disease was identified as a new type of coronavirus, similar to atypical pneumonia, or Severe Acute Respiratory Syndrome (SARS), which between 2002 and 2003 killed 650 people in mainland China and Hong Kong.

Cases of coronaviruses have, however, already been detected in the US, France, Canada, Australia, Singapore, Malaysia, Thailand, Japan, Vietnam, South Korea and Nepal.

Symptoms associated with infection by the virus – which has been given the provisional name of 2019-nCoV - are more intense than influenza and include fever, pain, general malaise and breathing difficulties such as shortness of breath.