WASHINGTON – The FBI is investigating allegations that computer hackers in China broke into Google’s email system, but no official government email accounts have been compromised, the Obama administration said Thursday.

“These allegations are very serious,” Secretary of State Hillary Rodham Clinton told reporters. “We take them seriously. We are looking into them.”

She had no comment on reports of China’s involvement.

Google said Wednesday that personal Gmail accounts of several hundred people, including senior U.S. government officials, military personnel and political activists, had been exposed. Google traced the origin of the attacks to Jinan, China, the home city of a military vocational school whose computers were linked to a more sophisticated assault on Google’s systems 17 months ago. The two attacks are not believed to be linked.

White House spokesman Jay Carney said the administration does not restrict government employees from using personal Gmail accounts, but does direct workers to use government email for official business. He had no comment on who in the administration may have been affected by the hacking.

The Pentagon said Thursday it had little information since the reported breaches involved personal accounts rather than government email. And since the accounts were not official, the U.S. Department of Defense didn’t know whether defense employees were among the targeted individuals.

A day after Google exposed the breach, China denied Thursday that it supports hacking and said it is part of global efforts to combat computer security threats.

“Allegations that the Chinese government supports hacking activities are completely unfounded,” said Foreign Ministry spokesman Hong Lei.

Google said all of the hacking victims have been notified and their accounts secured.