WASHINGTON -- Many scientists, including top US infectious disease expert Anthony Fauci, still believe that COVID-19 most likely occurred in nature and jumped from animals to humans, according to The Associated Press on Wednesday.

No new key scientific evidence that might make the lab-leak hypothesis more likely has been publicly identified by virus researchers, it added.

The World Health Organization said in March that COVID-19 introduction through a laboratory incident was considered to be an "extremely unlikely" pathway, refuting lab-leak theories.

"The great probability is still that this virus came from a wildlife reservoir," said Arinjay Banerjee, a virologist at the Vaccine and Infectious Disease Organization in Saskatchewan, Canada, according to the report.

Spillover events -- when viruses jump from animals to humans -- are common in nature, and have been seen in previous cases, he said.

Many scientists believe that it's unlikely the 90-day investigation by the intelligence community at the request of US President Joe Biden will yield definitive new answers, the report added.