SYDNEY (Reuters) - Australian logistics firm Qube Holdings Ltd (>> Qube Holdings Ltd) said on Friday it and partners had bought a near 20 percent stake in freight firm Asciano Ltd (>> Asciano Ltd), seeking to block a $6.5 billion bid from Canada's Brookfield Asset Management (>> Brookfield Asset Management Inc).

Confirming a Reuters report on Thursday, Qube said it had picked up a 19.99 percent stake, acting with Global Infrastructure Partners and Canada Pension Plan Investment Board.

Qube said it wanted to combine its logistics business with Asciano's Patrick Containers Terminal business, while GIP and CPPIB were interested in Asciano's Pacific National rail business.

"Qube believes that any transaction resulting in the combination of Qube with the Patrick Businesses, if it were to eventuate, would be highly accretive to Qube shareholders in the medium term," Qube said in a statement to the ASX.

Qube said its options now included voting against Brookfield's bid, talking to Brookfield and/or Asciano about an alternative proposal or holding its stake and seeking board representation.

Brookfield's mooted takeover would have been the largest-ever purchase of an Australian firm by a Canadian company and Australia's biggest inbound deal since 2011.

Since the company requires 75 percent of shareholders to vote in favor of the takeover, Qube's new holding was essentially a blocking stake, a person familiar with the matter told Reuters on Thursday.

Australia's competition regulator also raised antitrust concerns earlier this month because the deal would have given Brookfield Asciano's rail network and train operations in two of the country's eight states.

The Australian Competition and Consumer Commission (ACCC) had said it would give a final ruling by Dec. 17.

Qube closed on Thursday up 0.5 percent at A$2.20 a share on Australia's ASX exchange. Asciano ended flat at A$7.56, compared with Brookfield's A$9.15 offer price, reflecting investor doubts the deal will be consummated.

Qube said it had funded a 6.3 percent interest in Asciano via a deal with UBS [UBSAG.UL], with the remaining interest funded by GIP and CPPIB.

(Reporting by Lincoln Feast; editing by John Stonestreet and Cynthia Osterman)