WASHINGTON (Reuters) - A Chinese citizen was arrested in Chicago on Tuesday on charges that he covertly worked for a high-ranking Chinese intelligence official to help try to recruit engineers and scientists, including some who worked as U.S. defense contractors, the Justice Department said.

Ji Chaoqun, 27, first came to the United States in 2013 to study electrical engineering at the Illinois Institute of Technology, and in 2016 enlisted in the U.S. Army Reserves.

He appeared in a federal court in Chicago on one count of acting as an agent for the Chinese government. Laura Hoey, who is representing Ji in the case, could not immediately be reached for comment.

Speaking in Beijing on Wednesday, Chinese Foreign Ministry spokesman Geng Shuang he had “no understanding” of the situation. He did not elaborate.

According to the criminal complaint, Ji arrived in the United States from Beijing in August 2013 on a student visa, and went on to earn a Master’s Degree in electrical engineering in 2015.

Text messages reviewed by the Federal Bureau of Investigation showed that in November 2013, Ji was introduced to an intelligence officer from the Jiangsu Province Ministry of State Security, referred to in the complaint as “Intelligence Officer A,” by another person only identified as “Intelligence Officer B.”

They later met on several occasions in China, and initially the intelligence official told Ji he was a college professor, according to the complaint and affidavit filed by the FBI.

However, the FBI said, Ji eventually learned the person’s true identity and knew he was an officer in the Jiangsu Province Ministry of State Security, which is a provincial department of the Ministry of State Security.

A search warrant executed on an email account in 2015 later showed Ji had sent files to Intelligence Officer A containing information about eight different people based in the United States. The eight people were all naturalized citizens from Taiwan or China now living in the United States.

The Justice Department said all of them work for, or had retired from, jobs in the science and technology sectors, and that seven of the eight work or had worked for U.S. defense contractors.