He told The Mail On Sunday: “I’ve no idea at the moment when I will return. I hope it will be before the end of the season, but I’m not looking too far ahead.

“I’m taking it one day at a time.”

Murtagh’s problems stem from a back injury he suffered when thrown from a horse at Royal Ascot.

“I’ve had a lot of back pain ever since and at the moment I can’t run or put in the exercise that is required,” he said.

“My back is improving and at least I am riding again, but I am still sore on my side.

“The priority is to sort out my weight without having to run or spend hours in the sauna every day.”

Murtagh has enjoyed a terrific association with Alamshar this season, winning the Budweiser Irish Derby and King George VI And Queen Elizabeth Diamond Stakes on the John Oxx-trained colt.

The Aga Khan’s brilliant three-year-old is set to reappear in the Ireland The Food Island Champion Stakes at Leopardstown on Saturday, with Christophe Soumillon booked for the ride in the expected absence of his regular pilot.

However, Oxx appears not to have totally ruled out the possibility of Murtagh being on Alamshar at the weekend.

“It is amazing what some sea and sunshine and three square meals a day can do for a guy’s outlook,” he said.

“Johnny has returned in great shape and he partnered Alamshar in a piece of work on Friday morning.

“At this stage, I couldn’t say that he will definitely not ride Alamshar at Leopardstown.

“But I don’t want to say that he will because we don’t know how the next week will go.

“His weight has not shot up as badly as he feared and now it is coming down again.

“He does not want to rush back for Alamshar and abuse himself to make the weight.

“We are not putting any pressure on him.”