Telstra chief executive Andy Penn has ramped up his campaign against the National Broadband Network's pricing, complaining the system is warping the telecoms market and providing poor outcomes for retailers and consumers.

"What it’s doing is creating an unnatural distortion in the market where effectively the retail providers make no money through selling fixed broadband services in Australia," he said.

Telstra's Andy Penn said the NBN is distorting the market for broadband services. Credit: John Davidson

"In the long term, that can’t be good for customers, it can’t be good for investment, it can’t be good for the quality of telecommunication networks in Australia."

The NBN uncertainty is impacting the investment priorities of the major telcos as they prepare to launch 5G mobile networks, he told an event hosted by the Australian Financial Review.