The United States and China have traded accusations following a wave of cyberattacks targeting U.S. government agencies, media organizations, and private firms.
White House spokesman Jay Carney said the United States has "repeatedly" raised concerns about cybertheft with senior Chinese officials, including in the military.
China’s Foreign Ministry rejected accusations of government involvement in hacking as "groundless."
The ministry added that China itself was a major victim of hacking, and said most overseas cyberattacks on Chinese sites originated in the United States.
The exchange came as the Apple consumer-electronics company said it was recently attacked by hackers who infected Macintosh computers used by some employees.
U.S.-based Apple said there was no evidence consumer data was stolen. It was not immediately clear who was behind the attack.
The Chinese Foreign Ministry issued its statement after a U.S. security company released a report accusing a Chinese military unit in Shanghai of being behind a series of hacking attacks on U.S. government, corporations, and media companies.
The report by the Mandiant firm said its research had linked the People’s Liberation Army's "Unit 61398" to the theft of "hundreds of terabytes of data from at least 141 organizations across a diverse set of industries beginning as early as 2006."
It said most of the victims were located in the United States, with smaller numbers in Canada and Britain. The firm said the information stolen ranged from details on mergers and acquisitions to the e-mails of senior employees.
The report alleged that China’s military employs at least hundreds of expert hackers.
China Rejects Report
The Chinese Foreign Ministry rejected the report, calling it based on "rudimentary data."
Spokesman Hong Lei said that in 2012, foreign hackers had used viruses and other malicious software to seize control of 1,400 computers in China and 38,000 websites. He said hackers in the United States had carried out the highest number of attacks.
"China firmly opposes hacking, has implemented relevant laws and regulations, and adopted strict enforcement measures to prevent hacking activities," Hong said. "China is also a victim of Internet hacking attacks."
White House spokesman Carney said U.S. officials were aware of the Mandiant report, but declined to comment specifically on it.
Carney noted that President Barack Obama, in his State of the Union address last week, announced an executive order calling on U.S. officials to take action to better protect American agencies, companies, and critical infrastructure, such as power grids, from cyberattacks.
"It is a major challenge for us in the national security arena," Carney said. "The United States has substantial and growing concerns about the threats to U.S. economic and national security posed by cyberintrusions, including the theft of commercial information. As the president said in the State of the Union, quote, 'We know foreign countries and companies swipe our corporate secrets.'"
U.S. companies including "The New York Times," "The Wall Street Journal," the Facebook social-networking site, Twitter, and now Apple are among firms that have said they had recently been attacked by hackers.
With reporting by Reuters, AP, and AFP