Coronavirus has officially been declared a pandemic by the World Health Organisation (WHO).

Key points: The latest figures from Italy show the death rate from the disease there is more than 6 per cent

The latest figures from Italy show the death rate from the disease there is more than 6 per cent The WHO is calling on all countries to take "urgent and aggressive action"

The WHO is calling on all countries to take "urgent and aggressive action" There are now more than 118,000 cases in 114 countries and 4,291 people have died

WHO director-general Tedros Adhanom Ghebreyesus said the number of cases outside of China had increased 13-fold in the past two weeks, but added "all countries can change the course of this pandemic".

The announcement came as new figures from Italy showed the death rate among coronavirus patients in that country was more than 6 per cent, higher than the global average of about 3.6 per cent.

More than 800 people in Italy have now died and hundreds more are being treated for COVID-19 in hospital intensive care units.

Dr Tedros maintained the use of the word pandemic to describe the outbreak would not change the organisation's response.

"We are deeply concerned both by the alarming levels of spread and severity and by the alarming levels of inaction," he said.

"We have therefore made the assessment that COVID-19 can be characterised as a pandemic."

In the past two weeks the number of cases outside China had risen 13-fold, and the number of countries affected had tripled, Dr Tedros said.

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The coronavirus, which emerged in China in December, has spread around the world, halting industry, bringing flights to a standstill, closing schools and forcing the postponement of sporting events and concerts.

Tedros Adhanom Ghebreyesus warned all countries to get ready for the impact of coronavirus. ( Reuters: Denis Balibouse )

The WHO declared a public health emergency of international concern, its "highest level of alarm", on January 30 when there were fewer than 100 cases of COVID-19 outside China and eight cases of human-to-human transmission of the disease.

Now there are more than 118,000 cases in 114 countries and 4,291 people have died, with the numbers expected to climb.

Dr Tedros called on all countries to take "urgent and aggressive action".

"We cannot say this loudly enough, or clearly enough, or often enough: all countries can still change the course of this pandemic," he said.

"Ready your hospitals, protect and train your health workers, and let's all look out for each other because we need each other."

Death toll in Italy rises

Illustrating the severity and speed of the spread of the virus, Italian officials said the country now had 12,462 infections, a rise of more than 2,000, with 827 deaths.

They attributed the one-day increase to the heavily impacted Lombardy region not fully reporting its numbers on Tuesday.

Dr Mike Ryan, WHO's emergencies chief, gave a blunt warning about the urgency of the public health emergency.

"Iran and Italy are in the frontline now. They're suffering, but I guarantee you other countries will be in that situation soon."

Dr Ryan said the experience of South Korea, Singapore, and China in combating the new virus showed it could be controllable.

"We have observation that tells us that there is a strong element of controllability in this disease," he said.

"That doesn't mean we will completely stop it but what it does mean is there is a real chance to blunt the curve, there is a real chance to bend the curve and reduce the number of cases that our health system has to cope with and give the health system a chance to save more lives."

The WHO announcement has already caused chaos in the US stock market, with Wall Street plunging into a bear market — a sign of a recession — and the Australian market looks set for another difficult day.