Tan Hongjin, 35, was arrested in Oklahoma where he lived as a permanent resident.

The Justice Department said he stole trade secrets “related to a product worth more than $1 billion.”

Tan, who lived in the United States for 12 years and has a PhD from California Institute of Technology, allegedly illegally downloaded hundreds of company files which included intellectual property related to the manufacture of the “downstream energy market product.”

The department said he took the files for the benefit of a Chinese company that had offered him a job.

The employer was not identified, but a LinkedIn page identifies a materials scientist named Tan Hongjin as working for the Bartlesville, Oklahoma research center of Phillips 66, and Oklahoma media also linked him to the company.

The arrest came amid a broad US crackdown on Chinese government-backed hacking and theft of commercial data and secrets.

The Justice Department unveiled indictments against two hackers allegedly tied to Beijing's security services who operated as part of a multi-year plan to break into the computers of dozens of US companies and agencies.

“The Chinese government is attempting to acquire or steal not only the plans and intentions of the United States government, but also the ideas and innovations of the very people that make our economy so incredibly successful,” said Bill Priestap, head of the FBI's counterintelligence division to Congress.