Malcolm Turnbull has strongly hinted that he may sack members of the board of NBN Co if the Coalition is elected.
"It is remarkable that such a large board has no one with hands-on experience building or running a telecommunications network," he told the Nine Network's Financial Review on Sunday.
"People can draw their own conclusions from that."
The comments come after it emerged that the board of the federal government-owned company, led by chair Siobhan McKenna, had hired lobbying firm Bespoke Approach to talk up its achievements to Coalition MPs and save their jobs in the event of a change of government.
The news has raised allegations of misuse of taxpayers' funds.
An NBN Co spokesperson told AAP on Sunday that the board "often retains strategic advisers on various areas of the business".
McKenna has also been meeting senior bureaucrats outside the Department of Broadband for the same reason, according to a report in The Australian Financial Review.
The opposition has said it will review the AU$37.4 billion infrastructure project's board and management.
NBN Co chief executive Mike Quigley officially quit on Friday, although Turnbull said he had been axed.
The NBN is Australia's largest ever infrastructure project, aiming to deliver faster internet to millions of Australians through millions of kilometres of fibre optics.
However, it is behind schedule, and has been marred recently by asbestos mishandling scares at Telstra's NBN sites in NSW and the Coalition presenting its own cheaper broadband plan.
Turnbull said it is very questionable that expenses on lobbyists being borne by NBN Co are in the company's interests.
Bespoke was set up by and is run by senior political figures including former Liberal minister Alexander Downer, former Liberal staffer Ian Smith, and former Labor minister Nick Bolkus.