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 says a statement from Attorney-General Vickie Chapman is "wrong, discourteous and inappropriate".
His comments come 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.
But Mr Walker said he had only indicated he would withdraw the summonses if the state government had decided not to 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"The media release should be completely withdrawn.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."
In a reply to the commissioner, Ms Chapman confirmed the commission would not be extended and no further funding would be allocated.
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".
The commission was instigated by the former Labor state government, with now Opposition Leader Peter Malinauskas quick to defend it, describing the row as an extraordinary set of events.
"It is almost unprecedented in the history of our federation to see a royal commissioner be so clearly affronted by the remarks of the first law officer of a state," he said.
Mr Malinauskas called on Ms Chapman to issue an unreserved apology to Mr Walker and to grant the commissioner a time extension.
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.