Three researchers from China's Wuhan Institute of Virology (WIV) sought hospital care in November 2019, months before China disclosed the Covid-19 pandemic, the Wall Street Journal reported on Sunday, citing a previously undisclosed US intelligence report.

The newspaper said the report - which provides fresh details on the number of researchers affected, the timing of their illnesses, and their hospital visits - may add weight to calls for a broader probe of whether the Covid-19 virus could have escaped from the laboratory.

The report came on the eve of a meeting of the World Health Organisation's decision-making body, which is expected to discuss...