Hackers from China are believed to have attacked the computer systems of the New York Times (NYT) and Wall Street Journal (WSJ).
NYT said Chinese hackers have persistently penetrated its systems for the last four months and they broke into the e-mail accounts of its Shanghai bureau chief, David Barboza who wrote the reports on the Chinese prime minister Wen Jiabao's relatives.
Apart from Barboza, hackers also tried break into the e-mail accounts of the New York Times South Asia bureau chief in India Jim Yardley, who previously worked as bureau chief in Beijing.
NYT executive editor Jill Abramson said: "Computer security experts found no evidence that sensitive e-mails or files from the reporting of our articles about the Wen family were accessed, downloaded or copied."
WSJ publisher, Dow Jones & Co, said the paper's computer systems had been infiltrated by Chinese hackers, apparently to monitor its China coverage.
Paula Keve, a spokeswoman for Dow Jones, said: "Evidence shows that infiltration efforts target the monitoring of the Journal's coverage of China and are not an attempt to gain commercial advantage or to misappropriate customer information."
"Data security is an ongoing issue. We continue to work closely with the authorities and outside security specialists, taking extensive measures to protect our customers, employees, journalists and sources," Keve said.
WSJ said Chinese Embassy spokesman Geng Shuang condemned allegations of Chinese cyberspying. Shuang told WSJ "It is irresponsible to make such an allegation without solid proof and evidence."
"The Chinese government prohibits cyberattacks and has done what it can to combat such activities in accordance with Chinese laws. China has been a victim of cyberattacks."