Beijing accused the United States of "slander" on Wednesday after two Chinese nationals were indicted for seeking to steal coronavirus vaccine research and hacking hundreds of companies.
"The Chinese government is a staunch defender of cyber security, and has always opposed and cracked down on cyber attacks and cyber crime in all forms," said foreign ministry spokesman Wang Wenbin.
The US must "immediately stop its slander and smearing of China on cyber security issues," he told a regular press briefing in Beijing.
Li Xiaoyu, 34, and Dong Jiazhi, 33, targeted biotech companies but did not appear to have actually compromised any Covid-19 research, the US Justice Department said Tuesday.
Both are believed to be in China.
At a press conference, Assistant Attorney General John Demers said China had "now taken its place... in that shameful club of nations that provide a safe haven for cyber criminals."
But Beijing rejected the claims and said cyber space "should not become a new battleground".
"Those countries that seek cyber space hegemony will only hurt themselves," Wang said.
The indictment comes amid rising tensions between the global superpowers on a number of fronts, from trade to Beijing's handling of the coronavirus pandemic.