The Australian Consumer and Competition Commission (ACCC) has serious concerns about the $9 billion carve up of Asciano.

The deal has been set up to see a consortium led by the logistics group Qube join with investors led by Canada's Brookfield Infrastructure to buy Asciano's Patrick container business in a 50:50 joint venture.

Meanwhile, Asciano’s Pacific National rail business will be separated out and owned by investment partners of both Qube and Brookfield.

But ACCC Chairman Rod Sims says having numerous industry participants looking to gain market power from the vertical integration of Patrick joining with Australia’s two largest land-based logistics firms.

“The ACCC is concerned that Patrick container terminals may provide preferential access to Qube and ACFS vehicles, and Qube regional export trains running into Port Botany, and raise rivals' costs,” Mr Sims said.

“Qube and Brookfield will each own 50 per cent of Patrick container terminals, and may have parallel incentives to favour their landside logistics operations.”

The regulator is also concerned that the merger will put immense pressure on smaller stevedoring businesses.

“There are also concerns regarding foreclosure of rival stevedores,” Mr Sims noted.

“Market participants have suggested that if Patrick gives favourable treatment to the container logistics operations of both Qube and ACFS, then Qube and ACFS may provide a superior service offering to importers and exporters on condition that they use shipping lines calling at Patrick container terminals.

“This may lessen competition in stevedoring.”

But the ACCC has not actually blocked the deal.

Instead, it has called for industry feedback on any possible competition reduction at Australian ports and in land-based logistics and stevedoring if the deal were to go ahead.

Submissions to the ACCC are open until June 10.