NEW YORK - National League MVP Ryan Braun has tested positive for a performance-enhancing substance, a case still under appeal to an arbitrator under Major League Baseball's drug program, a person familiar with the situation told The AP.

The person spoke Saturday night on condition of anonymity because the appeal is still ongoing. The positive test was first reported by ESPN.

If Braun's appeal is denied, the Milwaukee Brewers star would be subject to a 50-game suspension.

Braun tested positive for elevated testosterone, ESPN said, adding that a later test determined the testosterone was synthetic.

If suspended, Braun would be eligible to return for Milwaukee's May 31 game at the Los Angeles Dodgers, barring any postponements. He would miss the first 57 days of the major league season, losing about $1.87 million of his $6 million salary

"There are highly unusual circumstances surrounding this case which will support Ryan's complete innocence and demonstrate that there was absolutely no intentional violation of the program," Braun's representatives at the Creative Artists Agency said in a statement. "While Ryan has impeccable character and no previous history, unfortunately, because of the process we have to maintain confidentiality and are not able to discuss it any further, but we are confident that he will ultimately be exonerated."

Under Major League Baseball's drug program, if a player appeals a first positive test for a performance-enhancing substance, an announcement isn't made until after a decision. Appeals usually are heard by Shyam Das.

The person familiar with the situation said Braun and others involved in the appeals process have known about the positive test since late October.

The 28-year-old outfielder hit .312 with 33 homers and 111 RBIs this year and led Milwaukee to the NL championship series, where the Brewers lost to the eventual World Series champion St. Louis Cardinals.

Braun already was signed through 2015 when the Brewers gave him a new deal running through 2020 that added $105 million and guaranteed him a total of $145.5 million over a decade.