(Reuters) - Goldman Sachs Group Inc (>> Goldman Sachs Group, Inc.) on Thursday sued CVR Energy Inc (>> CVR Energy, Inc.), an oil refiner controlled by Carl Icahn, contending that the billionaire investor will not let the company pay $18.5 million of fees and expenses it owes.

In a complaint filed with a New York state court in Manhattan, Goldman said CVR in March hired it to provide financial advice on Icahn's tender offer for its stock, and agreed to pay a fee based on the size of any transaction.

CVR requested an invoice, which Goldman sent on May 3, but four days later advised the bank that "Icahn had instructed CVR not to pay the invoice," according to the complaint.

Goldman said the amount due remains unpaid, and sued to recover it.

Icahn did not immediately respond to a request for comment. Goldman spokeswoman Tiffany Galvin declined immediate comment.

Last month, Icahn won control of CVR with an 80 percent stake after a majority of shareholders accepted his $30 per share tender offer, which valued the Sugar Land, Texas-based company at about $2.6 billion.

Icahn is now trying to sell CVR, and hired Jefferies & Co to advise on a possible sale. He has named ConocoPhillips (>> ConocoPhillips), HollyFrontier Corp (>> HollyFrontier Corp), Marathon Petroleum Corp (>> Marathon Petroleum Corp), Tesoro Corp (>> Tesoro Corporation), Valero Energy Corp (>> Valero Energy Corporation) and Western Refining Inc (>> Western Refining, Inc.) as possible buyers.

Forbes magazine in March estimated that Icahn is worth $14 billion.

The case is Goldman Sachs & Co v. CVR Energy Inc, New York State Supreme Court, New York County, No. 652149/2012.

(Reporting By Jonathan Stempel and Michael Erman in New York; Editing by David Gregorio)