NEW YORK (Reuters) - A U.S. judge denied bail on Thursday to a Chinese billionaire’s nephew whose construction company prosecutors say forced workers to provide private contracting work in violation of visas limiting their services to China’s U.N. mission and other sites.

Dan Zhong, a nephew of Chinese construction magnate Wang Wenliang, had sought to be released under a $10 million bond and live under house arrest under the watch of a private security firm paid $144,000 a month by his family members.

But U.S. District Judge Sterling Johnson in Brooklyn reversed a federal magistrate judge’s decision that had set those bail conditions, after prosecutors argued Zhong posed a flight risk.

Prosecutors cited Zhong’s access to vast wealth as giving him the means to flee. They said a co-defendant had already fled, and that several workers at Zhong’s company were leaving for China after receiving subpoenas.

“We’re concerned this defendant if bonded out will flee as well,” Assistant U.S. Attorney Alexander Solomon said.

Thomas Fitzpatrick, Zhong’s lawyer, declined comment. In court, he argued the bail conditions would have ensured there was “no reasonable way he could escape.”

Zhong, 46, was arrested on Nov. 10, becoming the latest Chinese national to face charges amid inter-connected probes involving federal prosecutors in Brooklyn and Manhattan.

Prosecutors say Zhong is the president of U.S. Rilin Corp, an affiliate of Wang Wenliang’s China Rilin Construction Group, and was previously an accredited Chinese diplomat.

Prosecutors said U.S. Rilin hired Chinese workers who received visas solely to perform construction work at China’s U.N. mission or other diplomatic facilities.

Instead, Solomon said, the company “used these worker to do private contracting work, basically using slave labor,” housing them in sub-par conditions and using “debt bondage” contracts to force them to stay.

Among the sites that court papers say received contracting work was a Long Island mansion owned by Qin Fei, a business associate of Ng Lap Seng, a Macau billionaire facing U.S. charges that he bribed an ex-U.N. General Assembly president.

Federal Bureau of Investigation agents last year interrogated Ng about Qin, asking if he was connected to foreign intelligence, records show. Ng has pleaded not guilty. Qin’s lawyer has not responded to requests for comment.

Wang could not be reached for comment. He was previously linked in May by CNN to an FBI probe that it said had examined campaign contributions he made to Virginia Governor Terry McAuliffe. Neither has been accused of wrongdoing.