A Chinese man pleaded guilty in a US federal court to pirating software that investigators said was worth more than $100 million, the US said Tuesday.

The US Immigration and Customs Enforcement said that it had broken up an operation run by Xiang Li, 36, of Chengdu in Sichuan, China, that the bureau called "one of the most significant cases of copyright infringement ever uncovered -- and dismantled."

Li distributed via his website Crack99.com hundreds of high-cost programs which he had "cracked," or broken access and license codes to allow anyone to use them, the ICE said in a statement.

The programs were used for defense, engineering of things like computer chips and aerospace materials, telecommunications, aerospace simulation, 3-D warfare, and computer-aided manufacturing.

Between 2008 and 2011 he sold software by some 200 different manufacturers to at least 325 buyers, ICE said, with more than one-third of the buyers in the United States, including a NASA engineer and a defense contractor.

ICE said Li had earned more than $60,000 dollars in the sales that it had documented to US buyers.

The agency said it had examined 25,000 emails on Li's Google Gmail account after obtaining a warrant.

Li was arrested in June 2011 after being lured by undercover buyers from ICE's Homeland Security Investigations division to the Pacific island of Saipan, in the US territory of the Northern Mariana Islands, to deliver pirated software.

"Li mistakenly thought he was safe from the long arm of HSI, hiding halfway around the world in cyberspace anonymity," ICE director John Morton said in a statement.

"Fast forward to today, where he is now being held accountable in Delaware for illegally stealing, distributing and ultimately exploiting American ingenuity and creativity at a loss of at least $100 million to US companies."

Li pleaded guilty on Monday to conspiracy to commit criminal copyright infringement and wire fraud in the US district court in Wilmington, Delaware, and faces up to 25 years in prison and a $250,000 fine.

He is scheduled to be sentenced on May 3.

Two US citizens, NASA engineer Cosburn Wedderburn and Wronald Best, chief scientist at a US defense contractor, have also pleaded guilty to copyright infringement and await sentencing.

Both bought programs which would have cost them hundreds of thousands of dollars to obtain legally.