One day after The New York Times reported that Chinese hackers had infiltrated its computers and stolen passwords for its employees, The Wall Street Journal announced that it too had been hacked.
On Thursday, The Journal reported that it had been attacked by Chinese hackers who were trying to monitor the company's coverage of China. It said hackers had broken into its network through computers in its Beijing bureau.
In a written statement, the business newspaper owned by News Corporation described the attack as an "ongoing issue" and said it was working closely with authorities and security specialists to clean up its systems. It said that it completed a "network overhaul" on Thursday in an effort to rid its systems of hackers.
China's Ministry of National Defense has denied any involvement in the cyberattack at The Times or any other American corporations.
But security experts said that in 2008, Chinese hackers began targeting American news organizations as part of an effort to monitor coverage of Chinese issues.
In a report for clients in December, Mandiant, a computer security company, said that over the course of several investigations it found evidence that Chinese hackers had stolen e-mails, contacts and files from more than 30 journalists and executives at Western news organizations, and had maintained a "short list" of journalists for repeated attacks. Among those targeted were journalists who had written about Chinese leaders, political and legal issues in China and the telecom giant Huawei.
Bloomberg News, another American news organization, was targeted by Chinese hackers last year, and some computers were infected, according to a person with knowledge of the company's internal investigation. The attack occurred after Bloomberg published an article on June 29 about the wealth accumulated by relatives of Xi Jinping, a Chinese official who is expected to become president in March.
Bloomberg has confirmed that hackers had made attempts but said that "no computer systems or computers were compromised."
The timing of the attacks on The New York Times coincided with the reporting for an investigation, published online on Oct. 25, that found that the relatives of Wen Jiabao, China's prime minister, had accumulated a fortune worth several billion dollars through business dealings.
Security experts hired by The Times to detect and block the computer attacks found digital evidence that Chinese hackers, using methods that some consultants have associated with the Chinese military in the past, breached The Times's network.
The Associated Press reported Thursday that officials in the Obama administration were considering more assertive action against Beijing to stop Chinese computer espionage campaigns.
The Secretary of State, Hillary Clinton, said Thursday a global effort was needed o establish "rules of the road" for cyber activity. In her final meeting with reporters at the State Department, Mrs. Clinton addressed a question about China's efforts to infiltrate computer systems at The New York Times.
"We have seen over the last years an increase in not only the hacking attempts on government institutions but also non-governmental ones," Mrs. Clinton said.
The Chinese, she said, "are not the only people who are hacking us."
"There is a lot that we are working on that will be deployed in the event that we don't get some kind of international effort under way," Mrs. Clinton added without elaborating.
The United States has been increasingly vocal about such efforts against government and private industry. In a November 2011 intelligence report, government officials specifically accused China and Russia of stealing intellectual property for economic gain.
Michael Gordon contributed reporting from Washington.
This article originally appeared in The New York Times.