Top-ranked UFC heavyweight contender Alistair Overeem, who is scheduled to face champion Junior dos Santos on May 26, failed a prefight drug test, Nevada Athletic Commission executive director Keith Kizer said Wednesday.

"The following athletes were tested on March 27: Alistair Overeem, Junior dos Santos, Frank Mir, Cain Velasquez, Roy Nelson and Antonio Silva," Kizer said in a statement. "All test results were negative, except Mr. Overeem tested positive for an increased T/E ratio (14 to 1, according to Kizer).

Fighters must not exceed a testosterone-to-epitestosterone ratio of 6-to-1.

The Dutch kickboxing champion can take a second urine test, but will need commission approval for a license to fight Dos Santos as scheduled May 26, Kizer said.

Overeem has denied past allegations of steroid use. His representatives did not immediately respond Wednesday to an Associated Press message left through Overeem's Las Vegas lawyer, David Chesnoff.

Upon receiving news of Overeem's test results, UFC president Dana White said, "I am beyond pissed about this. I'm so angry right now I can't even begin ..."

"It's beyond -- what's the word I'm looking for -- it's beyond belief," White said, as quoted by thestarphoenix.com."It's beyond comprehension. You're an absolute moron, a brain-dead absolute (expletive) dummy. It goes beyond a guy having any common sense whatsoever."

Dos Santos addressed Overeem's status on Twitter Thursday.

"I don't know anything more than you guys know and for me it's between him and the Nevada Athletic Commission," dos Santos said. "I am a professional and I'm the champion without ever having used anything for better performance results; when you guys see me fighting, that's really me."

Overeem, the former Strikeforce heavyweight champion, was slated to headline UFC 146 against dos Santos. The event's main card features all heavyweight bouts.

But Overeem's failed test puts his UFC title hopes in jeopardy.

Information from ESPN.com's Josh Gross and The Associated Press was used in this report.