Gaje Singh Hari Singh, Maryam Ahmad S A Al Boinin and Matter Said Khalfan Al Saadi were all sanctioned by the FEI Tribunal.

The trio's horses all tested positive for banned substance diisopropylamine, a drug used in the treatment of peripheral and cerebral vascular disorders which increases blood flow.

All three were provisionally suspended by the FEI in February with their bans back-dated to start on February 8.

They have all been fined CHF2,000 (£1,500/$2,000/€1,700) and must pay CHF1,000 (£760/$1,000/€860) in legal costs.

The trainer of all of the horses, Waleed Said Khalfan Al Saa'di, has been banned for 30 months, starting on February 9.

He has also been fined CHF3,000 (£2,300/$3,000/€2,600) plus CHF1,500 (£1,100/$1,500/€1,300) in costs.

Both Singh and Boinin's horses tested positive at an endurance event in Mesaieed in Qatar on November 11.

Qatar's Boinin rode Acqua Vela to victory in the 90 kilometre competition while India's Singh rode R S Nube Blanca over 120 kilometres.

Al Saadi, from Oman, rode Tarifa at an 80km event in the same Qatari city on January 7.

All three athletes and the trainer have 21 days to appeal the FEI's decision at the Court of Arbitration for Sport. 

The governing body also announced that they have provisionally suspended Colin Syquia of The Philippines after an adverse analytical finding.

His horse Adventure E tested positive for the sedative clomethiazole at the Southeast Asian Games in Malaysian capital Kuala Lumpur last month.