State toxicologist Ken Rudo testified that Governor Pat McCrory participated via phone in a meeting to draft letters to well owners downplaying the risk of coal ash contamination in their drinking water.
But speaking at a press conference late Tuesday night, McCrory's Chief of Staff Thomas Stith called that testimony false.
"Let me make it very clear, there was no meeting with the governor," said Stith, who also issued a statement on the claim. "That is a false statement, and Mr Rudo is just inaccurate."
Rudo alleges state officials watered down language warning well owners about the risk posed by a cancer-causing chemical linked to coal ash.
His testimony is part of a lawsuit filed by an environmental coalition pushing for Duke Energy to excavate its unlined coal ash pits. The Associated Press obtained the deposition earlier this week.
Lawyers for Duke Energy say they haven't had a chance to fully question Rudo. The utility had sought to keep Rudo's statement sealed, saying their attorneys did not have an adequate opportunity to question him.
Stith repeatedly denied that the Governor participated in the meeting. He said officials have been upfront about the risk posed by a cancer-causing chemical linked to coal ash.
"We're not going to stand by idly while individuals make false statements and lies under oath," Stith said.
In March, State Public Health Director Dr. Randall Williams reversed earlier warnings that had told hundreds of affected residents not to drink their water. Rudo testified his office was pressured by the Governor's administration to add misleading and confusing language to the warning letters to be sent to residents.
McCrory worked for Duke Energy for nearly three decades prior to his election. McCrory is running for re-election in November.