The authorities secured a guilty plea on Monday from a longtime employee of the Federal Bureau of Investigation accused of lying about his relationship with a Chinese technology company and various Chinese associates.

The government charged that the F.B.I. employee, Kun Shan Chun, had “expressed a willingness to facilitate the passage of sensitive United States government information” to his Chinese associates, including individuals with connections to the Chinese government.

Federal prosecutors in Manhattan said Mr. Chun had also lied to the bureau regarding his contact with these Chinese nationals and the firm based in China, Zhuhai Kolion Technology Company, “as part of a longstanding and concerted effort to conceal these relationships.”

Mr. Chun, who is known as Joey and worked in the bureau’s New York office, pleaded guilty before Magistrate Judge James C. Francis IV of Federal District Court in Manhattan to one count of acting in the United States as an agent of China. The charge carries a maximum prison term of 10 years, but the government and the defense agreed, under federal sentencing guidelines, that a sentence of 21 to 27 months would be appropriate, according to Mr. Chun’s plea agreement.