Wynn Resorts Ltd, the $15 billion gaming empire of Las Vegas tycoon Steve Wynn, may be forced to give its biggest shareholder access to its financial papers, a U.S. judge has ruled, the latest turn in a case that has transfixed the casino world with implications for the company's control.

The case has caused a bitter split between two self-made billionaires and former best friends and will now stretch on for at least two more weeks after the Nevada judge requested on Thursday more time to review the claims and give the business partners of 12 years an opportunity to resolve some issues.

Japanese businessman Kazuo Okada, who with close to 20 percent of Wynn Resorts holds more than double Steve Wynn's stake, is suing to gain access to financial information and has objected to a $135 million corporate donation to a university in the former Portuguese enclave of Macau as inappropriate.

The judge ordered Wynn Resorts to provide access to reasonable documents depending on the individual case and set the next hearing for February 23, spokesmen for both sides said.

A Hong Kong resident who made his fortune from pachinko machines, Okada, 69, has also nominated four potential candidates to Wynn's board, a move that could potentially give him influence over five out of 12 board seats.

The judge did not grant the relief Okada was seeking. The board will take the judge's request under advisement and report back in a couple of weeks, a Wynn spokesman told Reuters.

Okada is chairman of Universal Entertainment Corp -- an arcade-game manufacturer in which Goldman Sachs Group Inc has an 11 percent interest.

Universal is developing a $2 billion casino in the Philippines, which Wynn says is at the heart of the dispute between the two tycoons.

Wynn, 70, widely credited with transforming the Las Vegas Strip with icons such as the Treasure Island and sleek Bellagio casino properties, has said the fall-out began after he declined to work with Okada on the Philippines casino.

A spokesman for Okada rejected this claim, saying the Philippines project was not a factor.

We are pleased that the court has confirmed Mr Okada's right to inspection. Mr Okada looks forward to working with Wynn Resorts over the next two weeks, as directed by the court, to gain access to Wynn Resorts' books and records, said a spokesperson for Okada.

The fiery spat between Okada, an engineer by training who got his start fixing jukeboxes, and Wynn, known for upsetting shareholders more than 12 years ago with overzealous spending, may dampen Wynn's stock premium in the near term, analysts have said.

Shares of U.S.-listed Wynn Resorts and Hong Kong-listed unit Wynn Macau Ltd have been largely unaffected by the dispute so far. Wynn Resorts ended down 0.9 percent on Thursday, while Wynn Macau was down 0.4 percent by 0626 GMT on Friday.

($1 = 7.753 Hong Kong Dollars)

(Editing by Chris Lewis and Brian Rhoads)