National Broadband Network (NBN) CEO Mike Quigley has been the victim of a Coalition smear campaign that has cost Australian taxpayers’ huge money, the Minister for Broadband, Communication and the Digital Economy, Senator Stephen Conroy said on Friday.

Senator Conroy said the Coalition has forced NBN Co to commit tens of thousands of dollars of taxpayers' money to respond to a futile and malicious smear campaign against Mr Quigley.

According to him, the Senate Estimates hearing last night again vindicated Mr Quigley and proved he had not been involved in any wrongdoing at Alcatel-Lucent.

"Mike Quigley has been the victim of an appalling smear campaign and the evidence provided to the Senate Estimates hearing last night should end this matter once and for all," Senator Conroy said.

"As Mr Quigley explained yet again in a detailed statement to the Senate Estimates hearing, he was never involved, never investigated and never questioned about the corrupt activities of his previous employer.

"Last night's Senate Estimates hearing generated no new evidence that Mr Quigley had anything to do with the wrongdoing of Alcatel-Lucent in Central America seven years ago.

"The Coalition wasted the vast majority of the four hours of Senate Estimates time allocated to NBN Co, by attempting to re-litigate a five year investigation by the US Department of Justice and the Securities Exchange Commission which cleared Mr Quigley of any wrongdoing.