"The one consistent thing we've heard from all countries has been 'let's not politicize the science,' and the next thing that happens is the science is politicized. So what we want to do for all parties, and everybody is calling for this, there's widespread agreement amongst all our member states, let's not politicize the process," Mike Ryan told a briefing.
He said the WHO was engaged in "very positive consultations" with a large number of member states, including China, on how to proceed with the next stages of the inquiry.
"We're building on the report of the Phase 1 mission", Ryan added.
Last week, China's National Health Commission ruled out the second phase of the inquiry hapenning, calling its criteria "insulting." The United Nations responded by urging all member states to cooperate with the WHO in the inquiry.
In March, the WHO issued the first report of its fact-finding mission to China, which came to the conclusion that the possibility of the virus having leaked from a state laboratory in Wuhan was very low.