The royal commissioner leading South Australia's probe into the Murray-Darling Basin has called for an apology from the state's attorney-general amid a row over the future of his investigation.
Bret Walker said a statement from Attorney-General Vickie Chapman was "wrong, discourteous and inappropriate".
His comments came after Mr Chapman said Mr Walker would drop demands for commonwealth officials to appear at his inquiry.
Ms Chapman said he would withdraw a number of summonses for federal government and basin authority witnesses to give evidence.
Mr Walker's actions have been the subject of a High Court challenge by the commonwealth and Ms Chapman said she now expected that to be discontinued.
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But Mr Walker said he had only indicated that he would withdraw the summonses if the state government had decided not extend his commission.
He said if the High Court cleared the way for the summonses to be enforced, that could only be properly done so if the deadline for his report was pushed out.
"It is wrong to anticipate the withdrawal of the summonses by me, when that would follow only if the government's position was not definitely to extend the reporting time to enable their fair enforcement," Mr Walker said in a letter to Ms Chapman on Friday.
"The media release should be completely withdrawn. I am owed an apology."
The disagreement between the commissioner and the government comes after Premier Steven Marshall this week said the investigation continued to have his administration's support despite being "extraordinarily expensive".
"What we've got to make sure is that we get value for money, we get outcomes from this royal commission which are commensurate with the very, very high costs," he told reporters.
Mr Marshall said there were multiple investigations into water use under way and it was important that the royal commission did not double up with other inquiries.
"We've got to look at that space which is not being investigated, make sure that we are shining a light on the alleged water theft as it relates to areas which are not already being investigated," he said.
Mr Walker is examining a wide range of issues associated with the Murray-Darling Basin and the plan to ensure the future viability of the system.
He is particularly concerned with questions of water theft and rorting by upstream users and is currently due to report to the state government in February next year.
