Mark Benson in discussions with Australia's Ricky Ponting in Adelaide
English umpire Mark Benson has revealed he withdrew after the first day of the second Test between Australia and West Indies because of ill health.
There had been speculation that he walked out because he was unhappy with the new umpire review system.
Benson was reported to be furious that a not out decision he gave for a caught behind against Shivnarine Chanderpaul was overruled by the third umpire.
But in a statement Benson denied this and added he had not quit his job.
In the statement, released through the International Cricket Council, Benson said: "I would like to clarify that I have not resigned as an elite panel umpire.
"I had withdrawn after the first day's play as I felt that - due to my general health - I was not up to the task and it was in the best interests of the game, the ICC and myself that I step down and hand over to my colleague Asad Rauf.
"I have been in discussions with the ICC since my return from Australia and we have agreed that I will undergo a series of medical assessments. We will then discuss my future and my position as an ICC elite umpire.
"I would also like to state clearly that my withdrawal had nothing whatsoever to do with the decision review system (DRS).
"I remain a proponent of the use of technology as it helps the reduction of the obvious umpiring errors. The media speculation about the so-called disagreement in the umpires' room is unfounded and totally untrue."
ICC chief executive Haroon Lorgat added: "I sincerely hope that after Mark's clarification all speculation will be put to rest and the focus will return to the Perth Test."
Three years ago, former Kent pro Benson suffered heart palpitations during a Test in Durban and high blood pressure and stomach problems forced him out of the first four matches of Australia's one-day series in India at the end of October.
That referral system, you look at some umpires and you can see they're nervous but with him I've never really thought that
Former England captain Chris Cowdrey
Former England skipper Chris Cowdrey believes his predecessor as Kent captain, when he said he withdrew because of health.
He told BBC Radio Kent: "I do believe him. One thing he isn't is a quitter. He was always very unflappable. I am amazed it happened and can only think it must be because of illness.
"I know he hasn't been that well over the last two or three years so perhaps that wasn't such a surprise.
"That referral system, you look at some umpires and you can see they're nervous but with him I've never really thought that.
"I can't believe it's something that would have bothered him. It's a very strange thing to happen.
"I think he's beginning to be respected as one of the top boys. There's a lot of pressure on umpires but when you're under the spotlight all day, you make a split decision and having seen 35 replays we can all sit in our armchairs and say he made a bad decision, I'm not surprised it gets to some of these umpires. I have every sympathy with him."
The review system, which allows players to challenge decisions made by on-field umpires - forcing them to defer the decision to a colleague looking at video evidence - is not bedding in well.
Benson twice ruled West Indies batsman Chanderpaul not out on the first day of the match following appeals for caught behind by Australia.
Pakistan's Rauf, who was adjudicating as television umpire, upheld Benson's first ruling, much to the displeasure of the bowler Doug Bollinger and Australia captain Ricky Ponting.
However, Benson's second decision was overruled despite there being no clear evidence of contact with the bat from the 'Hot Spot' technology employed in the decision-review process.
The ICC's Dave Richardson defended the system, saying: "Trials were categorical in telling us that whereas before we got 92% to 93% of decision correct by using the new system we got 97% to 98% correct.
"What we tried to make sure when we rolled it out in this series was that there were always going to be times when the technology does not help."
England's high-profile four-Test series in South Africa, from 16 December, will also feature the new review system.