An international wrestling champion known as "The Carpathian Bear" was among 16 people detained as police busted a Romanian syndicate accused of the largest credit card data theft in Australian history.
The Australian Federal Police (AFP) say the syndicate had access to 500,000 Australian credit cards and about 30,000 were used to buy goods or services worth more than $30 million.
Announcing the bust on Thursday, the AFP said its joint operation with Romanian National Police involved a raid by 200 officers on 36 properties across Romania this week.
The investigation, codenamed Operation Lino, started in June 2011 when the AFP received a referral from an Australian financial institution related to suspicious credit card transactions, the AFP said in a statement.
Stolen credit card data was used to create false credit cards, enabling thousands of counterfeit transactions to be carried out in numerous overseas locations including Europe, Hong Kong, Australia and the United States.
The probe grew to involve law enforcement agencies in 13 countries, with the Australian banking and finance sector in strong support.
The AFP said 16 people were detained across Romania on Wednesday and seven were arrested and charged.
Among those detained but not arrested was international martial arts and Greco-Roman wrestling champ Gheorghe 'The Carpathian Bear' Ignat who had allegedly travelled to Australia in recent years.
The AFP said no Australian credit card holders lost money as a result of the fraudulent transactions, with Australian financial institutions reimbursing cardholders' losses.
AFP manager for Cyber Crime Operations, Commander Glen McEwen, said it was the largest data breach investigation ever undertaken by Australian law enforcement officers and the cooperation of other nations had been crucial.
"Today's successful outcome is a culmination of 17 months of hard work with these partners," he said.
Steven Munchenberg, chief executive of the Australian Bankers Association, congratulated police on their investigation.
He said banks had advanced monitoring systems to prevent fraud and had contacted customers and taken action to protect accounts when suspicious transactions occurred.
Commander McEwan urged credit card holders to keep their cards and PIN numbers secure, check ATMs for unusual attachments and check their financial statements regularly.