(Adds Santos and Macquarie statement, context,) Nov 16...

(Adds Santos and Macquarie statement, context,)

Nov 16 (Reuters) - Australia's competition watchdog said on Friday that it will not oppose oil and gas firm Santos Ltd's (STO) $2.15 billion acquisition of privately held Quadrant Energy.

The Australian Competition and Consumer Commission (ACCC)said in a statement that the acquisition would be unlikely to reduce competition in the supply of gas to Western Australia.

"The ACCC considers that a combined Santos/Quadrant will continue to face strong competition from a range of suppliers, including large LNG producers such as Chevron and Woodside," said ACCC Chair Rod Sims.

Santos said in a separate statement that the ACCC's approval cleared a condition for the acquisition, which is now expected to close "within weeks".

Santos had announced the buy in late-August, just a few weeks after Quadrant and its joint venture partner Carnarvon Petroleum (CVN) discovered an oil field that was touted as the biggest discovery off Western Australia for more than 20 years.

Separately, investment bank Macquarie Group Ltd (MQG) , which holds a 21.8 percent interest in Quadrant, raised its fiscal 2019 earnings outlook to 15 percent of growth from 10 percent, citing the ACCC approval.