THE decision by the Federation Equestre Internationale to allow the use of six previously banned drugs, including bute, on competition horses has stirred up a hornet's nest.

FEI vice-president Sven Holmberg opposed the move, saying he supported "100 per cent the clean sport program".

"The (new) progressive list cuts the legs off that," he said.

"It allows treatment of horses in competition and it will be rejected by the social media."

Mr Holmberg was addressing the 102 national federations in Copenhagen at the FEI's general assembly just before he was re-elected as chairman of the showjumping committee.

He said the FEI could expect an outcry from the equestrian media similar to the criticism it so disliked over the practice of "rollkur" in dressage, an exercise where the horse is made to practise with its head in a low position.

He said those who voted for the use of bute should "just wait to see what happens with this".

Frank Kempermann, who was elected as chairman of the FEI's dressage committee, also made no secret of his opposition to the new prohibited substances list.

"The FEI's decision is a contradiction to our idea of clean sport," Mr Kempermann said.

Leading equestrian vets have written to FEI president Princess Haya condemning the decision and asking her to reopen the debate.

Prof Leo Jeffcott, who was for many years based at the University of Melbourne Veterinary Hospital at Werribee and leader of the veterinary team at several Olympic Games and World Championships, was supported by leading vets from Australia, the US, Germany, France, and Finland in a letter that condemned the decision as premature, ill-considered and seriously retrograde".

The letter said the decision would have a negative effect on welfare and profound repercussions for equestrian sport.

The vets said allowing non-steroidal, anti-inflammatory drugs would lead to the abuse of horses because they would be made to compete when unfit.

The FEI said it released details of both lists to the national federations on November 13, but many present said the plans were a surprise.

An online petition has been set up to fight the new ruling. It can be reached by clicking here.