US President Joe Biden has signed a bipartisan bill that directs the federal government to declassify as much intelligence as possible about the origins of COVID-19, more than three years after the start of the pandemic.

The legislation, which passed both the House and Senate without dissent, directs the Office of the Director of National Intelligence to declassify intelligence related to China’s Wuhan Institute of Virology.

It cites “potential links” between the research that was done there and the outbreak of COVID-19, which the World Health Organisation declared a pandemic on March 11, 2020.

The law allows for redactions to protect sensitive sources and methods.

US intelligence agencies are divided over whether a lab leak or a spillover from animals is the likely source of the deadly virus.

Experts say the true origin of the coronavirus pandemic, which has killed more than 1.1 million in the US and millions more around the globe, may not be known for many years — if ever.

President Biden, in a statement, said he was pleased to sign the legislation.

“My administration will continue to review all classified information relating to COVID–19’s origins, including potential links to the Wuhan Institute of Virology,” he said.

“In implementing this legislation, my administration will declassify and share as much of that information as possible, consistent with my constitutional authority to protect against the disclosure of information that would harm national security.”