World Health Organization director-general Tedros Adhanom Ghebreyesus welcomed the joint WHO-China report on the origins of the coronavirus on Tuesday, but he noted that scientists had difficulty “accessing raw data” from China and called for further investigation of the lab leak theory.

Why it matters: The comments come in the wake of an inconclusive report that has prompted concerns about transparency and the influence of the Chinese government over the investigation.

Background: The report assessed that the coronavirus was most likely introduced to humans through an intermediate animal host, but called for further investigation in numerous areas — except for the theory that the virus leaked from a lab accident, which it called “extremely unlikely.”

What he’s saying: “I do not believe that this assessment was extensive enough,” Tedros said at a briefing on Tuesday. “Further data and studies will be needed to reach more robust conclusions.”

“Although the team has concluded that a laboratory leak is the least likely hypothesis, this requires further investigation, potentially with additional missions involving specialist experts, which I am ready to deploy.”The big picture: 14 countries — Australia, Canada, Czechia, Denmark, Estonia, Israel, Japan, Latvia, Lithuania, Norway, the Republic of Korea, Slovenia, the U.S. and the U.K. — released a joint statement on Tuesday expressing “shared concern” about the lack of access to “complete, original data and samples.”

Tedros, who was accused during the Trump administration of being beholden to China, appeared to echo some of those criticisms, saying, “In my discussions with the team, they expressed the difficulties they encountered in accessing raw data.””I expect future collaborative studies to include more timely and comprehensive data sharing,” he added.The bottom line: “Finding the origin of a virus takes time, and we owe it to the world to find the source so we can collectively take steps to reduce the risk of this happening again,” Tedros concluded. “No single research trip can provide all the answers.”

Go deeper: More findings from the report