Vaughan may have to contemplate further surgery on his knee

The decision to seek a fresh assessment followed a meeting between Vaughan and the England and Yorkshire physios.

There is still a possibility that he may require a fourth operation.

But Yorkshire chief executive Stewart Regan said: "Michael doesn't want to talk about it at the moment because he feels there is nothing new to say."

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He added: "The England and Wales Cricket Board are now in control of this and more information will be released later in the week."

Spinner Ashley Giles, meanwhile, has undergone a second hip operation after flying to Colorado in America to see a colleague of Dr Richard Steadman, the knee and shoulder specialist who operated on Simon Jones.

"They are world-class players. It's a big concern," coach Duncan Fletcher has admitted.

"I've adopted an attitude that if they do come back it will be a huge bonus."

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Fletcher believed Vaughan was progressing well until he suffered a setback during Yorkshire's match with Sussex and complained of soreness in his knee.

"There was a period when we thought it wouldn't be long before he was back, but after this injury they are going to have to re-assess it and we can make a decision from there," he added.

It is thought Vaughan, who opened the new Yorkshire club shop at Headingley on Tuesday with team-mate Matthew Hoggard, has a hole in his knee joint.

Surgery could either result in him being sidelined for eight to 10 weeks if they decide to clean out the knee or up to nine months if they repair the whole joint.

Neither he nor Giles, who were ever-present during last summer's Ashes triumph, have played for England since the tour of Pakistan.

There has been more positive news regarding Andrew Flintoff, who has missed the NatWest Series against Sri Lanka, with an ankle problem.

And pace bowler Simon Jones has insisted that reports sttating he would miss this winter's Ashes series because of a knee injury were premature.

"That's not true. I am working hard and the Ashes tour is a long way off - it's about five months or so.

"I've just got to get back bowling before then and prove my fitness.

"I want to get back into the side and the Ashes is a massive part of why you play cricket, so I am not going to discount myself yet."