(Adds quotes, deal context, decision deferral) SYDNEY, May 26...

(Adds quotes, deal context, decision deferral)

SYDNEY, May 26 (Reuters) - Australia's antitrust watchdog said on Thursday a proposed A$9.1 billion ($6.5 billion) buyout of rail and port giant Asciano Ltd (ASX) by a host of global investors may hurt competition in the rail freight industry.

The Australian Competition and Consumer Commission (ACCC) said the planned takeover by Canada's Brookfield Asset Management Inc and Australian cargo handler Qube Holdings Ltd (QUB) may give Qube unfair access to services contracts with Asciano's ports.

Asciano's port business "may provide preferential access to Qube and ACFS vehicles, and Qube regional export trains running into Port Botany, and raise rivals' costs", ACCC Chairman Rod Sims said. ACFS is a reference to Asciano's half-owned Australian Container Freight Services Pty Ltd.

"There are also concerns regarding foreclosure of rival stevedores," Sims added.

The ACCC has previously raised concerns about other aspects of the proposed deal, first announced a year ago. But it has been required to re-start its examination due to changes in the proposed deal itself, notably the decision by Brookfield and Qube to end a bid war and make a joint offer instead.

The ACCC had been scheduled to give its final ruling on whether to allow the takeover on Thursday, but said it was inviting more industry submissions and would now give its final decision on July 21. ($1 = 1.3920 Australian dollars)