A round-table conference hosted by the FEI unanimously agreed that any form of aggressive riding must lead to punishment under FEI rules.

The group, which included vets, welfare experts and eventing, dressage and show jumping officials, redefined rollkur or hyperflexion as "flexion of the horse's neck achieved through aggressive force".

They made a differentiation between rollkur and the technique of riding a horse in a low, deep and round outline, which is not achieved through force and therefore is not outlawed.

The meeting was held following a letter sent by British Horse Society chairman Patrick Print to FEI President Princess Haya demanding an investigation into the use of hyperflexion in dressage training.

Print demanded the FEI look into the apparent distress of Swedish rider Patrick Kittel's horse Watermill Scandic during the FEI Dressage World Cup at Odense last October, which was captured on video and sparked international outrage.

In the letter, he said: "You cannot be unaware of the disquiet - not to say anger - which has arisen following the depiction on Epona TV of Patrick Kittel's horse in apparent distress as it competed in Odense on 18th October."

Now a working group will be set up, headed by FEI dressage committee chairman Frank Kempermann, to expand guidelines for stewards to enable them to spot rollkur in the collecting ring.

They are also considering installing CCTV in warm-up areas at selected shows.