WASHINGTON (AP) — The Justice Department is charging two Chinese citizens with carrying out an extensive hacking campaign to steal data from U.S. companies.

An indictment was unsealed Thursday against Zhu Hua and Zhang Shillong, who prosecutors said were acting on behalf of China's main intelligence agency.

Court papers filed in Manhattan federal court allege the hackers were able to breach the computers of more than 45 entities in 12 states. The victims were in a variety of industries from aviation and space to pharmaceutical technology.

Prosecutors charge that the hackers were able to steal "hundreds of gigabytes" of data.

Court papers say they hacked computer service providers to gain access to the networks of businesses and governments in order to steal intellectual property and business data.

The indictment was to be announced Thursday by Deputy Attorney General Rod Rosenstein, FBI Director Chris Wray and Geoffrey Berman, the United States attorney in Manhattan.

Last week, officials from the Justice Department, the FBI and the Department of Homeland Security testified to the Senate Judiciary Committee that China is working to steal trade secrets and intellectual property from U.S. companies in order to harm America's economy and further its own development.

Chinese espionage efforts have become "the most severe counterintelligence threat facing our country today," Bill Priestap, the assistant director of the FBI's counterintelligence division, told the committee.

In the last several months, the Justice Department has filed charges against several Chinese intelligence officials and hackers. A case filed in October marked the first time that a Chinese Ministry of State Security officer was extradited to the United States to stand trial.