China wants foreign businesses to invest more in the country, but recent actions taken against foreign executives and a U.S. government employee are sending a chill. Chinese authorities have blocked a U.S.-based Wells Fargo banker from returning home, and separately sentenced a Japanese executive to more than three years’ imprisonment for espionage.

Though few details of the cases have been made known, they are a reminder of China’s expansive security apparatus and what to some executives, business groups and foreign governments is an opaque legal system that makes traveling to the country risky.

In a separate case, a U.S. government employee who had traveled to China on a personal trip has also been prevented from leaving the country for many weeks, said two people with a detailed knowledge of the case. The Washington Post reported on Sunday that the employee works in the United States for the Patent and Trademark Office, a unit of the Department of Commerce, and had gone to China to visit relatives there.

China has said little about either executive. Eric Zheng, the president of the American Chamber of Commerce in Shanghai, called for the release of more details in the Wells Fargo case in order to reassure the foreign business community.

Wells Fargo has suspended travel by its executives to China. Many Japanese companies have already been limiting travel to China and have been withdrawing family members of managers stationed in China.

The Wells Fargo executive, Mao Chenyue, was not detained. But she has been ordered not to leave China, according to the bank. “We are closely tracking this situation and working through the appropriate channels so our employee can return to the United States as soon as possible,” Wells Fargo said in a statement.

The exit ban on Ms. Mao was first reported by The Wall Street Journal.

Lin Jian, a foreign ministry spokesman, said this past week in response to each executive’s case that foreigners were subject to China’s laws while in the country. But he also said on Friday that “we always welcome enterprises from all countries to deepen their engagement in the Chinese market.”

Wells Fargo has not released any details of why Ms. Mao was prevented from leaving the country. Previous exit bans have sometimes involved situations when a large state-owned Chinese enterprise was investigating its own employees and wanted to compel an American executive with knowledge of the case to stay in China and testify against them.

A spokesperson from the United States Embassy in Beijing declined to comment on Ms. Mao’s case, but said, “We have raised our concern with Chinese authorities about the impact arbitrary exit bans on U.S. citizens have on our bilateral relations and urged them to immediately allow impacted U.S. citizens to return home.”

Foreign business interest in China has already been waning. A real estate crash has depressed consumer spending; regulatory obstacles hamper sales in China by foreign companies; and many industries face severe overcapacity.

Wells Fargo is one of six global banks that dominate the processing of dollar-denominated payments for China’s exports and imports. Ms. Mao is a Wells Fargo managing director who specializes in factoring: helping big companies that need dollars immediately to sell their right to payments due in a couple months from their overseas customers.

According to Ms. Mao’s LinkedIn profile, she has worked for a succession of U.S. financial institutions since 2000, most recently for Wells Fargo for more than 13 years. Her profile says that she is a native or bilingual speaker of Chinese and English.

Ms. Mao grew up in China and is a U.S. citizen now, said two people with knowledge of her situation who insisted on anonymity because of its political sensitivity.

Her case has prompted particular nervousness among naturalized American citizens who grew up in China, they said. The Chinese government has sometimes treated Americans who were born in China as Chinese citizens differently from other American citizens.

Such risks are reflected in the American government’s Level 2 travel advisory for mainland China, which says that citizens should “exercise increased caution” because of “arbitrary enforcement of local laws, including in relation to exit bans.” The State Department had only eased its travel alert in November from Level 3, which urged travelers to “reconsider travel” to China.

Companies and governments have also raised concerns that the broadening of counterespionage powers in China in recent years could put employees at foreign companies at risk of being targeted as spies for normal business practices such as gathering information on competitors, markets and industry.

On Wednesday, a Beijing court sentenced a longtime executive in China for Astellas Pharma of Japan to three and a half years in prison for espionage, according to the Japanese government, which expressed regret about the conviction. Neither China nor Japan has released details of that case or even officially confirmed the executive’s name. The executive was detained in 2023.

Alicia Chen contributed reporting.