ROME (AP) — A U.N. epidemiologist who publicly denounced the World Health Organization’s withdrawal of a report on Italy’s coronavirus response has resigned, citing the “unsustainable situation” he faced at the agency as a whistleblower.

Francesco Zambon said Thursday his resignation was effective March 31. He declined further comment other than to say it was “humanly and professionally” impossible for him to continue on his job.

Zambon had filed an internal ethics complaint with the WHO in May after he said he was pressured by a senior WHO official to falsify data to obscure that Italy hadn’t updated its influenza pandemic preparedness plan since 2006.

Zambon refused, and the report eventually was published noting the outdated plan and saying Italy’s initial response to the outbreak was “improvised, chaotic and creative.”

The WHO pulled the report from its website May 14, a day after it went up, and never republished it. The scandal over its withdrawal made headlines amid suggestions that the WHO spiked it to spare the Italian government criticism, embarrassment and liability.

The WHO said it contained “factual inaccuracies.” The agency added that it had created other ways of evaluating countries’ responses.

The missing report has featured into an investigation by prosecutors in Lombardy's Bergamo province, which was one of the hardest-hit provinces in the one-time epicenter of the European outbreak.

Prosecutors are investigating whether to lay any criminal blame for Italy’s horrific coronavirus toll, whether a lack of preparedness contributed to it and whether even the 2006 plan was ever implemented.

Zambon's resignation was first reported by state-run RAI's investigative Report program.