Raids and arrests in China have been made over the past two weeks in connection with a major software counterfeiter responsible for more than $2 billion in pirated Microsoft Corp. (NASDAQ: MSFT) software.

The software giant said Tuesday that the FBI and China's Public Security Bureau led a multiyear investigation into the syndicate, located in the Chinese province of Guangdong. The syndicate is the largest of its kind in the world, Microsoft said.

During the course of the multiyear investigation, more than 55,000 sophisticated-quality copies of counterfeit software were traced back to the same southern China criminal syndicate.

These counterfeit products came from seizures by law enforcement and customs authorities, through submissions made by Microsoft customers and partners, and from test purchases the company said.

“This case represents a milestone in the fight against software piracy — governments, law enforcement agencies and private companies working together with customers and software resellers to break up a massive international counterfeiting ring, said Brad Smith, senior vice president and general counsel at Microsoft.

The counterfeit software was found in 27 countries and five continents and included fake versions of Microsoft's most popular products, including Windows Vista and 2007 Microsoft Office.