The Australian Competition and Consumer Commission has kicked off its investigation into Pacific National's bid for Glencore's Hunter Valley coal haulage business. 

The competition regulator launched its review on Monday, seeking industry submissions by August 26. The ACCC said it would seek to rule on the proposed takeover on October 6. 

The review comes as Asciano's Pacific National, which is due to be acquired by a consortium of financial investors later this month after a prolonged takeover, seeks to acquire Glencore Rail. 

Pacific National already has an estimated 50 per cent share of the Hunter Valley coal haulage market, while the Genesee & Wyoming operated Glencore Rail has about 25 per cent. [Aurizon has the remaining 25 per cent.] 

Pacific National, Genesee & Wyoming and Aurizon are lining up to buy the business from Glencore. 

RBC Capital Markets is running an auction, which is into its second round. Aurizon's offer is already under review by the ACCC, with a ruling due on September 29. 

The Swiss giant's "GRail" coal haulage business was built back in 2010, and it was designed to carry up to 40 million tonnes of coal from Glencore mines to ships at the Port of Newcastle. The miner is expected to guarantee volumes to the network's new buyer, for at least the next 15-years.

GRail would be a logical first bolt-on acquisition for Pacific National's incoming owners which include Global Infrastructure Partners, the Canada Pension Plan Investment Board (CPPIB), China's CIC Capital Corporation, Singapore sovereign wealth fund GIC and the British Columbia Investment Management Corporation.