"All such alleged attacks are groundless, irresponsible accusations lacking solid proof or reliable research results," the spokesman said.
The Journal and Times said this week that Chinese hackers have attacked their computer systems to steal passwords of reporters and other staff members.
The Times said the hacks took place over the past four months, beginning during its investigation of the family wealth of former Chinese Premier Wen Jiabao. Hackers allegedly broke into the Journal's computers to monitor coverage of China.
A separate statement from the Chinese government said the military "has never supported any hacker activities."
CNN said one in every three computer attacks in the third quarter of 2012 originated in China.