A classified US intelligence report delivered to the White House was inconclusive on the origins of the Covid-19 pandemic, in part due to a lack of information from China, according to US media reports.

The assessment, which was ordered by US President Joe Biden 90 days ago, was unable to definitively conclude whether the virus that first emerged in central China had jumped to humans via animals or escaped a highly secure research facility in Wuhan, two US officials familiar with the matter told the Washington Post.

They said parts of the report could be declassified in the coming days.

The debate over the origins of the virus that has killed more than four million people and paralysed economies worldwide has become increasingly contentious.