The US has indicted five members of the Chinese military on charges they stole US secrets through hacking to help state-run companies.

A grand jury filed charges against five people in the People’s Liberation Army’s shadowy Unit 61398 for allegedly stealing steel industry secrets to benefit Chinese state-owned companies.

The criminal charges said that the hackers broke into US computers to gain a competitive advantage, hurting companies such as Westinghouse and the US Steel Corp as well as workers.

Attorney-General Eric Holder said the charges were the first of their kind against state actors and should serve as “a wake-up call”.

“This administration will not tolerate actions by any nation that seeks to illegally sabotage American companies and undermine the integrity of fair competition in the operation of the free market,” Holder told reporters on Monday.

“The indictment makes clear that state actors who engage in economic espionage, even over the Internet from faraway offices in Shanghai, will be exposed for their criminal conduct and sought for apprehension and prosecution in an American court of law,” he said.

The charges, which US officials said came after several years of investigation, were filed against Wang Dong, Sun Kailiang, Wen Xinyu, Huang Zhenyu and Gu Chunhui.

China has issued a statement denying the charges saying it is a victim of American-espionage.