WASHINGTON: 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 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.

Those tensions are expected to complicate the state visit to Washington next month by Xi Jinping, the Chinese president.

The work of the agents is a departure from the routine practice of secret government intelligence gathering that the United States and China have carried out on each other’s soil for decades. The Central Intelligence Agency has a cadre of spies in China, just as China has long deployed its own intelligence operatives into the United States to steal political, economic, military and industrial secrets.

In this case, said American officials, who discussed details of the operation only on the condition of anonymity because of the tense diplomacy surrounding the issue, the Chinese agents are undercover operatives with the ministry of public security, China’s law enforcement branch charged with carrying out Operation Fox Hunt.

The campaign, a central element of Xi’s wider battle against corruption, has proved popular with the Chinese public. Since 2014, according to the ministry of public security, more than 930 suspects have been repatriated, including more than 70 who have returned this year voluntarily, the ministry’s website reported in June. According to Chinese media accounts, teams of agents have been dispatched around the globe.

American officials said they had solid evidence that the Chinese agents — who are not in the United States on acknowledged government business, and most likely are entering on tourist or trade visas — use various strong-arm tactics to get fugitives to return. The harassment, which has included threats against family members in China, has intensified recently, officials said.

The officials declined to provide specific evidence of the activities of the agents.

The United States has its own history of sending operatives undercover to other nations — sometimes under orders to kidnap or kill. In the years after the September 11, 2001, attacks, the CIA dispatched teams abroad to snatch Qaeda suspects and spirit them either to secret CIA prisons or hand them over to other governments for interrogation.

Neither China’s ministry of public security nor the ministry of foreign affairs responded to faxes requesting comment. But Chinese officials have often boasted about their global efforts to hunt economic fugitives, and the state news media has featured reports detailing the aims and successes of Operation Fox Hunt.

According to the Chinese news media, Beijing has sent scores of security agents abroad to “persuade” their targets to return home. Just how they accomplish their aims is unclear, and questions have been raised about why a number of suspects, presumably sitting on significant wealth abroad, have willingly returned to China.

Liu Dong, a director of Operation Fox Hunt, has said Chinese agents must comply with local laws abroad and that they depend on cooperation with the police in other countries, according to a news report last year. But in a telling admission, he added, “Our principle is thus: Whether or not there is an agreement in place, as long as there is information that there is a criminal suspect, we will chase them over there, we will take our work to them, anywhere.”

It is unclear whether the FBI or the Department of Homeland Security has advocated within the Obama administration to have the Chinese agents expelled from the country, but the White House decision to have the state department issue a warning to the Chinese government about the activities could be one initial step in the process.