No customer data was stolen from The Times, security experts said.
Asked about evidence that indicated the hacking originated in China, and possibly with the military, China's Ministry of National Defence said, "Chinese laws prohibit any action including hacking that damages internet security." It added that "to accuse the Chinese military of launching cyberattacks without solid proof is unprofessional and baseless".
The attacks appear to be part of a broader computer espionage campaign against US media companies that have reported on Chinese leaders and corporations.
Last year, Bloomberg News was targeted by Chinese hackers, and some employees' computers were infected, according to a person with knowledge of the company's internal investigation, after Bloomberg published an article June 29 about the wealth accumulated by relatives of Xi Jinping, China's vice president at the time. Xi became general secretary of the Communist Party in November and is expected to become president in March. Ty Trippet, a spokesman for Bloomberg, confirmed that hackers had made attempts but said that "no computer systems or computers were compromised".
Signs of a campaign
The mounting number of attacks that have been traced back to China suggest that hackers there are behind a far-reaching spying campaign aimed at an expanding set of targets including corporations, government agencies, activist groups and media organisations inside the United States. The intelligence-gathering campaign, foreign policy experts and computer security researchers say, is as much about trying to control China's public image, domestically and abroad, as it is about stealing trade secrets.
Security experts said that beginning in 2008, Chinese hackers began targeting Western journalists as part of an effort to identify and intimidate their sources and contacts, and to anticipate stories that might damage the reputations of Chinese leaders.
In a December intelligence report for clients, Mandiant said that over the course of several investigations it found evidence that Chinese hackers had stolen emails, contacts and files from more than 30 journalists and executives at Western news organisations, and had maintained a "short list" of journalists whose accounts they repeatedly attack.
While computer security experts say China is most active and persistent, it is not alone in using computer attacks for a variety of national purposes, including corporate espionage. The United States, Israel, Russia and Iran, among others, are suspected of developing and deploying cyberweapons.
The United States and Israel have never publicly acknowledged it, but evidence indicates that they released a sophisticated computer virus in 2012 that attacked and caused damage at Iran's main nuclear enrichment plant. Iran is believed to have responded with computer attacks on U.S. targets, including U.S. banks and foreign oil companies.
Sign up for CIO Asia eNewsletters.