The World Health Organization on Monday admitted an error in its assessment of the global risk of a deadly virus in China, saying it was "high" and not "moderate".

The Geneva-based UN health agency said in a situation report published late Sunday that the risk was "very high in China, high at the regional level and high at the global level."

In a footnote, the WHO explained that it had stated "incorrectly" in its previous reports on Thursday, Friday and Saturday that the global risk was "moderate".

The correction of the global risk assessment does not mean that an international health emergency has been declared.

WHO spokeswoman Fadela Chaib said only that there had been "an error in the wording".

Asked what the risk categorisation meant, the WHO said it was "a global evaluation of risk, covering severity, spread and capacity to cope".

The WHO on Thursday had stopped short of declaring the novel coronavirus a public health emergency of international concern -- a rare designation used only for the most severe outbreaks that could trigger more concerted global action.

WHO chief Tedros Adhanom Ghebreyesus, who is visiting China this week to discuss how to contain the outbreak, on Thursday said: "This is an emergency in China, but it has not yet become a global health emergency".

WHO's cautious approach can be seen in the context of past criticism over its slow or too hasty use of the term, first used for the deadly 2009 H1N1 swine flu pandemic.

During that outbreak, the UN health agency was criticised for sparking panic-buying of vaccines with its announcement that year that the outbreak had reached pandemic proportions, and then anger when it turned out the virus was not nearly as dangerous as first thought.

But in 2014, the WHO met harsh criticism for dragging its feet and downplaying the severity of the Ebola epidemic that ravaged three West Africa countries, claiming more than 11,300 lives by the time it ended in 2016.