Sept 21 (Reuters) - Transurban Group, Australia's largest toll road operator, has been blocked from buying a majority interest in Horizon Roads in the third rejection from the country's regulator on a big ticket corporate takeover in the past year.

The Australian Competition and Consumer Commission (ACCC) said on Thursday it opposed Transurban's plans to take a stake in the company, which holds a concession from the State of Victoria to operate the 39-kilometre-long EastLink toll road in Melbourne until November 2043.

The deal had been valued at A$2 billion ($1.29 billion) by local media reports.

Transurban shares fell 2.2% to A$12.85 in early trade, outpacing a 0.6% decline in the broader S&P/ASX200 index.

"The proposed acquisition would result in Transurban entrenching its position in Victoria, and prevent the entry of a rival operator, which could compete closely for future toll road concessions in Victoria," ACCC Chair Gina Cass-Gottlieb said.

Transurban, in a separate statement, noted the ACCC's decision "with disappointment", and said it will consider all options available to it.

Last December, the regulator had blocked an asset transfer deal between wireless internet firms and major telco firms Telstra Group and TPG Telecom.

The Australian Competition Tribunal upheld the decision in June after an appeal from the companies.

The ACCC also blocked ANZ Group in August from buying Suncorp's banking business for A$4.9 billion.

The future of Brookfield Corp's A$15.3 billion bid for Origin Energy, the largest buyout in Australia this year, will be known when a decision is due to be handed down on Oct. 12.

($1 = 1.5559 Australian dollars)

(Reporting by Scott Murdoch in Sydney and John Biju in Bengaluru; Editing by Sherry Jacob-Phillips)