The head of Australia's competition watchdog says the owners of monopoly infrastructure such as Newcastle port are "clearly winning" their battle with regulators.
Australian Competition and Consumer Commission boss Rod Sims told the Australasian Transport Research Forum in Canberra on Monday that Treasurer Josh Frydenberg's decision to allow the deregulation of Newcastle's shipping channel was "bad for the economy".
Mr Frydenberg last week endorsed a National Competition Council ruling that the port's private operators can set their own fees for ships using the channel, angering the NSW Minerals Council and mining giant Glencore.
The ACCC will no longer act as an arbiter of pricing disputes between the port's owners and users.
Mr Sims said on Monday that monopolists controlling "bottleneck" infrastructure had a "clear incentive to maximise profits by raising prices, even if this means ... less use of their service".
"It is bad for the economy when bottleneck infrastructure, at the end of a crucial value chain, is in the hands of a company with unfettered market power," he said.
"A monopolist in that situation will always use its power. The question is only by how much and how often.
"How is it that Australia, much more so than other countries we compare ourselves to, allows this?"
The ACCC ordered the port to lower its prices by 20 per cent last year after an application from Glencore.
Mr Sims echoed the Minerals Council's criticism that the deregulation of the port would limit investment due to the absence of a "credible threat of arbitration".
He said the port's deregulation was the first test of 2017 amendments to the Competition and Consumer Act's infrastructure access provisions and showed that "vertically separated" infrastructure such as ports, railways and airports needed a "market power" test or the kind of "bespoke regulation" applied to the electricity and gas networks.
"Why regulate energy monopolies but not transport monopolies?" he said.