Spanish police working with the US Secret Service have shut down a criminal network that pocketed more than €12 million via a credit card fraud that extended across more than 15 countries, authorities said.

More than 100 alleged members of the network were arrested in a trans-Atlantic operation, a Spanish National Police statement said.

It said the fraudsters took advantage of a legal loophole that allows US credit card holders to make purchases in Europe with no funds, while banks on both continents settle the transactions.

Even though the transactions were eventually rejected, the vendors - in this case mainly complicit hotels, bars and restaurants - kept the money.

They would then transfer the funds back to the ring, which was headquartered in a hotel in the small western Spanish town of Miajadas, keeping a slice for themselves as a commission, the police statement said.

Overall the network spanned more than three U.S. states and15 European countries, including Spain, Greece, Austria, Britain, Denmark, Ukraine and Germany, it said.