Romanian hackers have stolen more than $25 million from half a million Australian credit cards, coppers have confirmed.
Australian Federal Police confirmed they were working with law enforcement bodies in other countries to tackle the organised hackers.
The attacks seem to have come after the hackers took out several merchants whose individual computer systems have been compromised.
According to the The Age, the same hacker group is believed to have been responsible for a hack of US Subway restaurants.
Four Romanians have been charged over millions of dollars in credit card fraud affecting about 80,000 customers.
The syndicate found its victims by scanning the internet for vulnerable point of sale terminals.
Aussie police said that the borderless nature of this crime provides some new headaches for coppers.
Not only do they need to co-operate with other police forces, but they need international and private sector co-operation to take down the criminals.
But it is a little difficult to stop. Hackers are finding softer targets with local chippies with insecure point of sale machines than they do with banks and supermarket chains.