The Obama administration has delivered a warning to Beijing about the presence of Chinese government agents operating secretly in the United States to pressure prominent expatriates — some wanted in China on charges of corruption — to return home immediately, according to American officials.

The American officials said that Chinese law enforcement agents covertly in this country are part of Beijing’s global campaign to hunt down and repatriate Chinese fugitives living abroad and, in some cases, recover allegedly ill-gotten gains. The Chinese government has officially named the effort Operation Fox Hunt.

The American warning, which was delivered to Chinese officials in recent weeks and demanded a halt to the activities, reflects escalating anger in Washington about intimidation tactics used by the agents. And it comes at a time of growing tension between Washington and Beijing on a number of issues: from the computer theft of millions of government personnel files that American officials suspect was directed by China, to China’s crackdown on civil liberties, to the devaluation of its currency.