O'Brien and Murtagh have had Group One wins with Duke of Marmalade

Jockeys Johnny Murtagh and Colm O'Donoghue and trainer Aidan O'Brien have been found guilty of breaching the rules of racing at a hearing in London.

A British Horseracing Authority (BHA) inquiry looked into Duke of Marmalade's Juddmonte International Stakes victory at Newmarket on 23 August.

Murtagh and O'Donoghue were handed seven-day riding bans by the panel, while O'Brien was fined �5,000.

The trio were summoned over a possible breach of "team tactics" rules.

Both jockeys will be free to ride in the Prix de l'Arc de Triomphe at Longchamp on 5 October.

BHA spokesman Paul Struthers said after the hearing: "I would like to stress that in reaching their conclusions the panel made clear that there was no attempt to cheat, simply that the breaches occurred due to ignorance of the details of the rule in question."

O'Donoghue, who was riding the pacemaker Red Rock Canyon in the Group One event, admitted a breach of the rules, making a manoeuvre in a race in the interest of another horse in common ownership.

The inquiry panel found Murtagh in breach of Rule 220 (iii) in that he acted in a manner prejudicial to the proper conduct of racing, while the panel ruled that O'Brien failed to give adequate instructions concerning the rules of racing.

606: DEBATE Give your reaction to the inquiry news

O'Donoghue's mount moved off the rail, allowing Murtagh to take the gap and eventually claim the race.

In a surprise development, it emerged on Tuesday that triple Epsom Derby winner Murtagh had also been called to the inquiry.

The panel concluded the 38-year-old, number one rider to Irish champion trainer O'Brien, had breached rules in that he "instructed, directed or encouraged O'Donoghue to ride in the way he did".

Duke of Marmalade's triumph was one of 20 Group One victories so far this season for champion Irish trainer O'Brien, who is chasing a world record 26.

In the immediate aftermath of the race, the BHA had indicated Murtagh would not face disciplinary action.

After the hearing, the trio refused to comment.