The UK Serious Organised Crime Agency (SOCA) has closed 36 website domains selling compromised card data, as a part of it an ongoing anti-cyber fraud campaign in conjunction with the Federal Bureau of Investigation (FBI).
SOCA confirmed it had also arrested two British men caught making purchases on the sites but said it was unable to provide information on the specific sites taken offline.
"Two arrests were made, one in Stanford, Birmingham and one in Tottenham, London. Both were caught making large scale purchases, bulk buying card details, presumably with the intention to commit fraud," a SOCA spokesman told V3.
SOCA said the sites were "automated vending carts" (AVC) and said their existence was proof that cyber criminals and gangs are developing new, more dangerous techniques, and streamlining their operations.
"AVC's use the same type of technology as any other e-commerce site. They look the same and operate like legitimate businesses," said the spokesman.
"We've seen a rapid shift in the number of criminals using AVCs as their preferred means of selling."
The spokesman confirmed that SOCA has been working with numerous other law enforcement agencies including the FBI and Australian Federal Police to track and hamper AVC rings for some time.
The agency claims that the joint operations have already recovered over 2.5 million items of compromised personal and financial information over the past two years.
Earlier this year SOCA took down a music file-sharing site called rnbxclusive.com and threatened users they could face 10 years in jail or an unlimited fines for downloading illegal content, although later backed down on this threat.
F-Secure chief research officer Mikko Hypponen praised the actions of SOCA but said law enforcement agencies have a long way to go before they cause any significant damage to cyber criminals' wider operations.
"I'm glad to see authorities focus their efforts on the online attackers that hurt us the most: organised criminal gangs," he told V3.
"Taking 36 carding sites down is great news. But it's not over. Many large sites continue operating normally."
Hypponen's comments come after he claimed law enforcement agencies spend too much time tackling copyright infringers and hacktivists rather than true cyber criminals.