The "whole world needs to be on alert" over the new coronavirus outbreak, the World Health Organisation (WHO) said as it reconsiders whether to declare a global health emergency.

It comes as the death toll in China passed 130 and cases of human-to-human transmission were confirmed in at least three other countries.

Its emergency committee, which said last week it was "too early" to pronounce a global health emergency, will meet for a second time on Thursday.

Dr Michael Ryan, executive director at the WHO Health Emergencies Programme, said the decision to reconvene was due to the increasing number of cases and evidence of person-to-person transmission of the virus.

He told a press conference in Geneva that the Chinese government deserves "huge credit" for its response and transparency regarding the "extraordinary challenge".

He said: "The whole world needs to be on alert now, the whole world needs to take action and be ready for any cases that come, either from the original epicentre or from other epicentres that become established."

A benefit of the emergency committee meeting could be to align the various measures being taken by countries on borders and travel.

Dr Ryan said multiple countries implementing measures at different times based on their individual risk assessments was a "potential recipe for disaster, at least politically, economically and socially".

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The WHO said person-to-person transmission had been confirmed in three countries outside China - Japan, Vietnam and Germany.

Director-general Tedros Adhanom Ghebreyesus told the conference: "The continued increase in cases and the evidence of human-to-human transmission outside China are, of course, most deeply concerning.

"Although the numbers outside China are relatively small, they hold the potential for a much larger outbreak."

He added that China "deserves our gratitude and respect" for its "extraordinary" efforts to prevent the spread of cases outside the country.

He continued: "But make no mistake, I am not saying although it is 68 now, it may not be bigger. It may be bigger and we may even face serious problems.

"That's why, when we see the human-to-human transmission in three countries, we are reconvening the emergency committee to understand what that means."