European and US intelligence agencies have cracked an international ring of credit card fraudsters and arrested 61 people, Europol said Tuesday.

In a joint operation by Europol, the US secret service and Bulgarian police on July 6, 47 suspects were detained in Bulgaria, nine in Italy, two each in Spain and the United States and one in Poland.

The Bulgaria-based masterminds behind the organised crime group suspected of copying, or "skimming" more than 15,000 payment cards are among those arrested.

Spanish police said the gang had been active for nine years.

Europol estimated the group had clocked up over 50 million euros ($70 million) in damages for EU citizens by skimming their cards and emptying their bank accounts.

Skimming occurs when a card is put through an illegal device, normally attached to an ATM or point-of-sale terminal at a retail outlet, for the purposes of copying data from its magnetic strip to make a clone.

The Europe-wide police agency said in a statement the group was "one of the largest criminal gangs known to have been active in this field in the last five years".

More than 200 police officers were involved in what was codenamed Operation Night Clone.

The group had links to crime organisations in Kenya, South Africa and the United States, and also recruited and trained petty criminals to illegally withdraw money with the false cards.

Organised crime groups have been known for some time to target the vulnerability of payment cards with magnetic strips.

"Within the EU, criminals work has been made more difficult with the full implementation of EMV technology (chip and PIN), but criminals have since exploited a loophole in these security arrangements by making illegal transactions with EU issued cards in non-EMV compliant regions, including Africa and the USA," said Europol.

"Payment cards in the EU are targeted for cloning, and the fraud committed in other regions which still accept payment by magnetic strip."

The Eu, with a population of half a billion people, is the worlds largest market for payment card transactions and, in 2009, organised crime groups derived more than 1.5 billion euros from payment card fraud in the EU, the agency said.