Two UK men have pleaded guilty to charges related to the infamous DarkMarket payment-card fraud ring busted by authorities in October 2008, according to British police.

Renukanth Subramaniam, 33, and John Michael Francis McHugh, 66, both pleaded guilty to conspiracy to defraud in Blackfriars Crown Court in London on Thursday.

DarkMarket was a highly organised, password-protected online forum where criminals worldwide could buy and sell credit card numbers, a practice known as "carding." Since its shutdown, more than 60 people have been arrested by law enforcement agencies in the UK, U.S., Germany, Turkey and other countries.

Subramanian was an "itinerant loner" who was allegedly observed selling lists of credit cards near the Java Bean Internet Café in Wembley where he frequently accessed the DarkMarket site, according to the Serious Organised Crime Agency (SOCA).

He used a memory stick to carry data around and seemed to think using Internet cafes would help shield his activities, SOCA said.

Subramanian had no fixed address and frequently stayed with friends but had mortgaged three houses, SOCA said. In the past, Subramanian had worked for Pizza Hut and a dispatch company.

McHugh was arrested in December 2008 after investigators found he was allegedly running a counterfeit credit card factory, SOCA said. McHugh, a retiree who lived in Doncaster, England, allegedly had details for more than 2,000 credit cards in his home along with a "suite of images and logos" needed to produce fake cards.

No sentencing date has been set for the men.

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FBI investigators spent three years clandestinely infiltrating the DarkMarket forum, building trust with those running the site before making dozens of arrests in October 2008 in conjunction with SOCA and the U.S Secret Service. Investigators said the arrests likely prevented an additional $70 million in payment card fraud.

Twelve DarkMarket suspects were arrested in the UK. One of those arrested was Adewale Taiwo, a Nigerian national sentenced to five years in prison in January 2009 for conspiracy to defraud. SOCA said he admitted to causing £600,000 (US$960,000) of fraud although banks stopped £240,000.

The DarkMarket Web site had more than 2,500 members when it was shut down. Members were carefully vetted by others to try and keep out law enforcement. Members could sell payment card details as well as buy equipment needed to make fraudulent cards.