Godolphin are to face no further charges in relation to a doping scandal that resulted in one of the stable's leading trainers being banned from racing for eight years, the British Horseracing Authority said on Thursday.

The BHA said there was no evidence that anyone other than Mahmood Al Zarooni was involved in the case at the Gulf outfit's stables in Newmarket, eastern England.

Al Zarooni was suspended and later banned in April this year after 22 horses, including last season's St Leger winner Encke, tested positive for banned anabolic steroids.

BHA director of integrity, legal and risk, Adam Brickell, said an investigation had found no new evidence to contradict the original findings.

"The evidence gathered from this investigation has confirmed that Mahmood Al Zarooni acted autonomously and was the person solely responsible for the events that took place at Moulton Paddocks," he said in a statement on britishhorseracing.com.

"However, we have identified significant failings in the processes in place and management structure at the yard which allowed these events to unfold without senior management becoming aware. These findings have been shared with Godolphin."

The BHA and Godolphin both confirmed that Al Zarooni's 38-year-old assistant, Charlie Appleby, would assume control of Moulton Paddocks with immediate effect and be in charge of some 200 racehorses.

Appleby, who will work alongside fellow trainer Saeed bin Suroor, said in a statement on godolphin.com: "My main way of repaying Godolphin will be by producing winners and good horses."

Al Zarooni initially appealed against his ban for "widespread systematic misuse of illegal substances" but in May withdrew his case.

The scandal has been described as the most serious in the recent history of British racing and led Godolphin owner Sheikh Mohammed bin Rashid Al Maktoum to declare himself "appalled and angered" by Al Zarooni's actions.

The Dubai ruler in May issued a decree banning anabolic steroids in all horse-related sports in the United Arab Emirates.

Anabolic steroids are banned in Britain but were allowed out of competition in countries including Australia, Dubai and the United States.