China on Tuesday expressed indignation and resolute opposition to advertisements run by the San Francisco bureau of the FBI in local Chinese language newspapers.

The advertisements purportedly asked readers to report on any foreign power trying to gather information that could harm the United States, and specifically mentioned China, implying that the Chinese Ministry of State Security had infringed on US security interests.

"The contents of the advertisements by the United States side are groundless, and China is indignant about them," Chinese Foreign Ministry spokesman Qin Gang said at a regular press conference.

Qin said Chinese security departments safeguarded the nation's security interests in full respect of the law, and had never tried to subvert foreign governments, infringe on their sovereignty or territorial integrity, or undermine their security interests.

He said a handful of Americans were trapped in cold war ways of thinking and keen to disseminate the "China threat theory".

"Their activities are unpopular and will get nowhere," Qin said.

He urged the US to take effective measures to repair the negative impact of the advertisements and refrain from doing anything to undermine Sino-US relations and disturb the friendship between the two peoples.