Godolphin racing manager Simon Crisford spoke of "a terrible day for British racing" after trainer Mahmood Al Zarooni was disqualified for eight years after admitting administering anabolic steroids to horses in his care.

Al Zarooni said he had made a "catastrophic error" in using the banned drugs on a number of runners in his yard, including former 1000 Guineas favourite Certify.

Al Zarooni was called before the British Horseracing Authority disciplinary panel at a hastily-arranged hearing on Thursday afternoon after 11 horses returned positive samples for ethylestranol and stanozolol following a random testing at his Newmarket yard earlier this month.

Further admissions were made by Al Zarooni to the BHA this week surrounding four other horses that had not been tested.

The case, widely regarded to be the most serious doping scandal in recent British racing history, had already caused Godolphin principal Sheikh Mohammed to lock down Al Zarooni's stables, saying he was "appalled and angered" by events.

Al Zarooni, 37, was officially charged with rule breaches related to prohibited substances, duty to keep medication records and conduct prejudicial to racing.

Earlier in the day, the fifteen horses were banned from running for six months from April 9.

"This is a terrible situation. It's an awful situation that Godolphin has found themselves in," Crisford said.

"Mr Al Zarooni acted with awful recklessness and caused tremendous damage, not only to Godolphin and British racing.

"I think it will take a very long time for Godolphin to regain the trust of the British public.

"We're shocked and completely outraged by the actions he has taken."

Crisford also confirmed Al Zarooni had mentioned the names of three other people - two foremen and a veterinary assistant - who were "involved".

However, he said the assistant had not broken any rules because he was unaware what substance he was administering.

Referring to the contravention of British rules, he said: "This is an isolated incident at the hands of a reckless person who has shown no respect for horse racing in this country."

Asked about Sheikh Mohammed's views on the incident in Britain, Crisford said: "He will want, first and foremost, to see this put behind us. He will want to make sure this mistake never happens again."

Al Zarooni issued a statement that read: "I would like to apologise to Sheikh Mohammed, as well as to all those involved with Godolphin and the public who follow British racing.

"I can only apologise and repeat what I said in my statement earlier in the week, I have made a catastrophic error."

BHA chief executive Paul Bittar said he believed the punishment would reassure the public and the racing industry that the use of performance-enhancing drugs would not be tolerated.

The BHA's investigation established that the substances in question were administered on the instruction of Al Zarooni.

He said the full details of how the substances were administered would be published later.