According to the Justice Department, admissions from Western Union show that between 2004 and 2012 the firm violated US laws by processing hundreds of thousands of transactions for its agents and others involved in an international consumer fraud scheme.

Crooks contacted victims in the US and falsely posed as family members in need or promised prizes or job opportunities before directing the dupes to send money through Western Union to help their relative or claim their prize.

Various Western Union agents were complicit in these schemes, often processing the fraud payments for the fraudsters in return for a cut of the proceeds, say authorities.

Western Union is accused of knowing about the suspect agents yet refused to take action. For years the firm recorded customer complaints but failed to follow its own proposed guidelines on suspending agents.

Meanwhile, officials say that they also uncovered hundreds of millions of dollars being sent to China in structured transactions designed to avoid the reporting requirements of the Bank Secrecy Act. Much of the money was sent to China by illegal immigrants to pay their human smugglers.

Acting Assistant Attorney General Bitkower says: "As this case shows, wiring money can be the fastest way to send it - directly into the pockets of criminals and scam artists. Western Union is now paying the price for placing profits ahead of its own customers."

In a statement, Western Union says: "We share the government’s goal of protecting consumers and the integrity of our global money transfer network, and we worked hard to resolve these matters with the government."