The Wall Street Journal said Thursday it had been targeted by hackers trying to monitor the newspaper's coverage of China, less than a day after a similar revelation from its competitor The New York Times.

The Journal, which is owned by News Corp., said it finished an overhaul of its IT systems on Thursday aimed at strengthening its networks.

"We continue to work closely with the authorities and outside security specialists, taking extensive measures to protect our customers, employees, journalists and sources," the Journal said in a statement.

In recent years, security experts have uncovered many cyberattacks that aimed to steal intellectual property or spy on certain groups, including nongovernmental and political organizations.

The campaigns often use spear-phishing attacks, which involve sending targeted emails to individuals that try to persuade them to visit a malicious website or open a file that installs malicious software on their computer. Installing a type of malware called a backdoor allows hackers to quietly syphon off information.

The attacks are difficult to detect, as customized pieces of malware frequently escape detection by security software.

In an article about the attacks, The Wall Street Journal provided few details but said hackers gained access to its computer systems through its Beijing bureau, citing anonymous sources familiar with the incident.

The newspaper said it believes the intrusions were for the "apparent purpose of monitoring the newspaper's China coverage."

The New York Times said late Wednesday that China-based hackers had stolen passwords and gained access to email accounts for employees of the company. Two reporters were targeted, one of whom wrote an exposA(c) published in October about the finances of China's prime minister, Wen Jiabao, and his family.

After the story was published, the Times said it noticed network activity consistent with cyberattacks linked to China's military. With an outside consultant, Mandiant, the newspaper found its systems hosted 45 pieces of custom malicious software. The newspaper informed the U.S. Federal Bureau of Investigation.

The Wall Street Journal said the FBI has been investigating cyberattacks directed at publishers for more than a year.

An FBI spokeswoman reached on Thursday said the agency could not comment on the reports.

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