The International Cricket Council says it needs to find out more about umpire Mark Benson's sudden withdrawal during a Test match in Australia.
Benson left the Adelaide test after the first day and his future now appears to be in doubt.
There had been suggestions that the Englishman had walked out as a protest of the the new umpire review system in Tests.
The ICC's general manager Dave Richardson says incidents on the field didn't force the umpire to leave the test.
Mark Benson has been on the Elite panel since 2006 and has stood in 26 tests and 72 ODI's.