Officials from the foreign ministry in China have denied accusations from The New York Times that Chinese hackers repeatedly penetrated the newspaper's computer systems over the past four months.
Last year the paper published a story alleging relatives of Premier Wen Jiabao controlled assets worth worth at least $US2.7 billion.
The paper said security experts had digital evidence that the hackers had used methods which have been associated with the Chinese military.
China's foreign ministry dismissed the accusations as "groundless".
"To arbitrarily assert and to conclude without hard evidence that China participated in such hacking attacks is totally irresponsible," said spokesman Hong Lei.
"China is also a victim of hacking attacks. Chinese laws clearly forbid hacking attacks, and we hope relevant parties takes a responsible attitude on this issue."
The BBC reports Beijing has been accused by several governments, foreign companies and organisations of carrying out extensive cyber espionage for many years, seeking to gather information and to control China's image.
According to the Times, the hackers first broke into their computer system in September, as the report on Mr Wen was nearing completion.
The report, which was dismissed as a "smear" by the Chinese government, said Mr Wen's relatives had amassed assets worth at least $US2.7 billion through business dealings. It did not accuse the premier of wrongdoing.
WSJ also
The Wall Street Journal also says its computer systems have been infiltrated.
The Journal said the hackers were trying to monitor its China coverage.
Publisher Dow Jones & Co issued a statement on Thursday saying hacking attacks related to its China coverage were "an ongoing issue".
