Four international airlines have agreed to pay $504 million in fines to settle charges they conspired to fleece consumers by driving up cargo shipping prices.

The Justice Department called the case one of the largest antitrust settlements in U.S. history.

Associate Attorney General Kevin O’Connor called the scam an “international price-fixing cartel” that cost consumers hundreds of millions of dollars between 2001 and 2006. In some instances, for example, fuel surcharges rose by 1,000 percent.

One of the four airlines _ Air France-KLM _ has agreed to pay $350 million of the total settlement.

The investigation is continuing.