Former Secretary of State Mike Pompeo said Sunday that he believes the coronavirus pandemic originated with a leak out of a lab in Wuhan, China, and that under the Trump administration the U.S. came close to uncovering the details of how it began.

During an interview on "Fox News Sunday," Pompeo took issue with a question about the Trump administration failing to get enough information from China about the origins of COVID-19.

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"We have a really good idea what happened here," Pompeo said. "There is an enormous amount of evidence that there was a leak from the Wuhan Institute of Virology. There is a pile of evidence a hundred feet high, I have high confidence that that’s the case. We pressed the Chinese Communist Party really hard – not just the State Department, but our CDC and others too."

Pompeo went on to say that the administration was "serious in this endeavor" and that it "made clear that there would be real cost" to the Chinese government.

An advisory board member to the World Health Organization told Fox News last week that China's "massive cover-up" on COVID-19 is still happening today as the Wuhan lab-leak origin theory gains momentum.

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"The Chinese have engaged in a massive cover-up that is going on until this day, involving destroying samples, hiding records, placing a universal gag order on Chinese scientists and imprisoning Chinese citizen journalists asking the most basic questions," Jamie Metzl told "America's Newsroom."

Pompeo said Sunday that the U.S. had been "very close to being able to make a lay-down case for what actually happened" with COVID-19. 

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"We know enough now, the cover-up continues, and it’s time for accountability," he said.

Asked point-blank if he believes that the virus came from a leak out of the Wuhan Institute, Pompeo said, "I do."

A top Chinese diplomat reportedly told current Secretary of State Antony Blinken on Friday that the lab-leak theory was "absurd."

Blinken, meanwhile, "stressed the importance of cooperation and transparency regarding the origin of the virus, including the need for WHO Phase 2 expert-led studies in China," a State Department press release said.

Fox News’ Megan Gallen contributed to this report.