Experts examining the origins of the coronavirus first identified in China will follow up on an initial report released this week but details are still not set, World Health Organization Director-General Tedros Adhanom Ghebreyesus told a news conference on Thursday.

"There will be follow-up assessments, that's what we expect," he told an online briefing, adding "engagements" would start as soon as possible.

Data was withheld from investigators who travelled to China to research the origins of the epidemic, Tedros had said on Tuesday when the report was released.