Authorities in the US and China have broken up a piracy group accused of trafficking more than $2bn worth of unlicensed software.

The group operated CD production plants throughout the Guangdong province in southern China, according to Microsoft, producing more than five million copies of counterfeit Microsoft products. 

The ring is thought to be one of the largest in the world, and Microsoft predicts that the bust will lead to a "significant decrease" in the volume of pirated software worldwide.

Among the 13 products were versions of Windows Vista, Office 2007, XP and Windows Server.

Microsoft has collected more than 55,000 copies of the pirated software from customers, although the company believes that this represents fewer than one per cent of the pirate group's actual shipments.

Samples of the pirated products were collected in 27 countries, and included versions in English, Croatian, Dutch, German, Spanish, Italian, Korean and Simplified Chinese.

"This case represents a milestone in the fight against software piracy," said Brad Smith, senior vice president and general council at Microsoft.

"Governments, law enforcement agencies and private companies have worked with customers and software resellers to break up a massive international counterfeiting ring."

The move is the latest in an anti-piracy campaign from Microsoft that has seen multiple arrests and dozens of lawsuits since 2006 in an effort to reduce the trafficking of counterfeit software. 

It is estimated that software vendors worldwide lost more than $40bn in revenue last year due to pirated goods.