LAS Vegas cab driver Gerardo Gamboa thought someone left a bag of chocolates in the back seat. But this stash turned out to be cold hard cash.

The Las Vegas Review-Journal reports that Mr Gamboa was making a pick up on Monday at the Bellagio hotel and casino when a hotel doorman noticed the brown paper bag and handed it to him.

At a red light, the Checker Cab driver's curiosity got the best of him. To his surprise, he found six bundles of $US100 bills totaling $US300,000 ($336,000).

The newspaper reports that Mr Gamboa called his dispatcher and took the money to the company's main office.

Las Vegas police and casino officials were able to link the money to a well-known poker player they declined to identify.

It's unknown whether Mr Gamboa will receive a big Christmas tip.