The head of a World Health Organisation-led team probing the origins of Covid-19 said bats remain a likely source and that transmission of the virus via frozen food is a possibility that warrants further investigation, but he ruled out a lab leak.

Peter Ben Embarek, who led the team of independent experts in its nearly month-long visit to the Chinese city of Wuhan, where the outbreak first emerged at a seafood market in late 2019, said the team’s work had uncovered new information but had not dramatically changed their picture of the outbreak.

“The possible path from whatever original animal species all the way through to the Huanan market could have taken a very long and convoluted path involving also movements across borders,” Embarek told a nearly three-hour media briefing.

Embarek said work to identify the coronavirus’s origins points to a natural reservoir in bats, but it is unlikely that they were in Wuhan.