However, the council is continuing to investigate Mr Whiting's claims, at the council's cost, chief executive Duncan Field confirmed yesterday.
Mr Whiting sent his apology to mayor Clive Geddes on Tuesday, after making his comment at a public forum during a council meeting in Wanaka on March 31.
Mr Geddes said at the time he would order an immediate inquiry and that is now being undertaken by Dr Royden Somerville QC.
Mr Whiting yesterday gave the media a copy of his letter, in which he said he wished to "sincerely apologise to [the mayor], the councillors and the councillors' staff for any distress" and that he wanted to formally withdraw the use of the word "corrupt".
"As you may have noted I was not working from any script and the word was ill considered. Nevertheless I still have concerns about the process that was followed ... and welcome the investigation proposed.
"I have full confidence in Dr Somerville's independence and experience to carry it out and appreciate this step being taken," Mr Whiting said.
QLDC chief executive Duncan Field yesterday said the council was continuing the investigation because Mr Whiting still had concerns over the processes used by council and saw value in the process.
Dr Somerville's status "befits the seriousness of the complaints", Mr Field said.
"[The] council will pay for this exercise. The cost is unknown although I expect it to be several thousand dollars. He will be in town on April 20 and will begin the project then. It may take several weeks before I receive his report," Mr Field said.
