Melbourne Cup-winning jockey Michelle Payne was contrite and “embarrassed” after being hit with a four-week riding suspension for a positive drug test.

Payne, who rose to prominence after riding 100-1 shot Prince of Penzance to win the 2015 cup, was found with banned substance Phentermine – an appetite suppressant – in her system after providing a urine sample at a meeting in Swan Hill, in northern Victoria, on June 11.

She attended Racing Victoria headquarters at Flemington on Thursday to plead guilty to the charge and is now banned from riding until July 21.

Payne’s legal team unsuccessfully argued for a lighter ban, insisting that the 31-year-old was prescribed Phentermine to help treat symptoms relating to a horror the jockey experienced in 2016.

But Payne will not appeal the decision, insisting that she took “full responsibility” for the punishment.

“The onus is 100 per cent with me … I regret not seeking more guidance,” she said afterwards.

“I wasn’t thorough, and that is completely my fault. My sincere apologies to everyone.

“I accept the stewards’ decision … I look forward to working hard and being in great shape upon my return to racing.”

Payne’s team provided letters to Racing Victoria stewards from her treating physician and surgeon in a bid to reduce the penalty.

But the stewards, who said they took into account Payne’s guilty plea, remorse, good record and “some medical circumstances”, insisted she was aware Phentermine was a banned substance.

The suspension is slightly back-dated, taking in the six days Payne had not ridden since being made aware of her positive test on June 23.

Payne said during the inquiry that she was “embarrassed” with the attention her positive test received.

“I really regret being here today,” she said.

“I’m embarrassed and I apologise … I’m sorry.”

The penalty was described as “appropriate and fair” by the chairman of the Australia Jockeys Association, Des O’Keeffe.

O’Keeffe later responded to comments made by former jockey Dylan Dunn, who told The New Daily the use of appetite suppressants by jockeys was common.

“The testing doesn’t indicate that,” O’Keeffe told The New Daily.

“The amount of irregularities we get, for the amount of tests that are taken, is really small.

“I’d respect his view … [but] all the hard evidence doesn’t indicate that that’s the case.”

The length of the ban ensures Payne, whose most recent ride was at England’s Royal Ascot last week, when she steered 40-1 long-shot, Kaspersky, to fifth in the Queen Anne Stakes, will be able to keep her ride at the same track in August.

Payne has been booked to ride in the Shergar Cup at the iconic English venue, on August 12.

The punishment will not interfere with Payne’s training of horses, nor her ability to ride track work.