The U.S. State Department summoned the Chinese ambassador to the United States on Friday to protest against comments by Beijing suggesting the U.S. military might have brought the coronavirus to Wuhan, as tensions between the two global powers over the outbreak intensified.

David Stillwell, the top U.S. diplomat for East Asia, delivered a very "stern representation" to China's ambassador Cui Tiankai, a State Department official said, adding that Beijing's envoy was "very defensive."

The State Department official, who spoke on condition of anonymity, said China was seeking to deflect criticism of its role in "starting a global pandemic and not telling the world."