He made the remark amid renewed scrutiny of the theory that the COVID-19 pandemic emerged from the secretive lab.

"What I can say for sure is this: we know that they were engaged in efforts connected to the People's Liberation Army inside of that laboratory, so military activity being performed alongside what they claimed was just good old civilian research," Pompeo said on "Fox & Friends Weekend."

"They refuse to tell us what it was, they refuse to describe the nature of either of those, they refused to allow access to the World Health Organization when it tried to get in there," he said.

The virus, which is believed to have originated from China, has now spread across the globe.