• Trainer Bob Baffert was temporarily suspended by New York racing officials from entering horses — including Kentucky Derby winner Medina Spirit — in the upcoming Belmont Stakes.
• The suspension, which also applies to two other thoroughbred tracks in New York, is due in part to Medina Spirit's positive test for the steroid betamethasone after the Derby.
• Medina Spirit finished third in the Preakness Stakes, the second leg of racing's Triple Crown, which was won by Rombauer.

The trainer Bob Baffert was temporarily suspended Monday from entering horses — including Kentucky Derby winner Medina Spirit — in next month's Belmont Stakes or races at other major New York tracks due to Medina Spirit's positive test for a banned drug after its Derby victory.

The suspension comes two days after Medina Spirit finished third in the Preakness Stakes — the second jewel in thoroughbred racing's Triple Crown — and as Baffert awaits a second test that could erase Medina Spirit's Derby win.

Medina Spirit tested positive for 21 picograms of the steroid betamethasone on the day of the Derby at Churchill Downs in Louisville, Kentucky, according to Baffert.

While that drug can be legally used as a therapeutic in Kentucky on a horse, any trace of it on race day is grounds for disqualification if a second test confirms it was in the blood on that day.

The New York Racing Association said its decision to bar Baffert's horses, for now, took into account not only the Derby probe, but also "the fact that other horses trained by Mr. Baffert have failed drug tests in the recent past, resulting in the assessment of penalties against him by thoroughbred racing regulators in Kentucky, California, and Arkansas."

The suspension applies to any Baffert horses entering races or occupying stall space at Belmont Park, Saratoga Race Course and Aqueduct Racetrack, the state's three major thoroughbred racing venues.

New York Racing Association CEO Dave O'Rourke said, "In order to maintain a successful thoroughbred racing industry in New York, NYRA must protect the integrity of the sport for our fans, the betting public and racing participants."

"That responsibility demands the action taken today in the best interests of thoroughbred racing," O'Rourke said.

The racing association said it "expects to make a final determination regarding the length and terms of Mr. Baffert's suspension based on information revealed during the course of the ongoing investigation in Kentucky, such as the post-Kentucky Derby test results of Medina Spirit."

Maryland racing officials last week allowed Medina Spirit and another Baffert-trained horse, Concert Tour, to enter the Preakness after getting what they called "a binding commitment" from Baffert for "full transparency of medical and testing results that will allow for all results to be released to the public.

Rombauer won the Preakness, followed by Midnight Bourbon and Medina Spirit. Concert Tour finished ninth.

The Belmont Stakes, which is the third leg of the Triple Crown, is scheduled for June 5.

Marty Irby, executive director of the advocacy group Animal Wellness Action and a critic of Baffert, said in a statement, "We applaud NYRA's decision to suspend Bob Baffert following Medina Spirit's failed Derby Day drug test. "

"Horse protection advocates will rest easier knowing that Baffert won't be competing at the 2021 Belmont Stakes," Irby said.

"NYRA was a tremendous partner in ushering the Horseracing Integrity and Safety Act to passage and we're elated to see the State of New York continues to make the welfare of the horse, and eradicating cheaters from the industry, a top priority. It's time to end doping in the fastest two minutes in sports."

Disclosure: CNBC parent NBCUniversal owns NBC and NBC Sports, which broadcast the Triple Crown races.

Correction: An earlier version of this article incorrectly reported that there was a maximum allowable limit of betamethasone in a horse on race day in Kentucky under regulations there. In fact, any trace of that steroid in a horse is grounds for disqualification if subsequent testing confirms its presence on race day.