UPDATE 5-Australian gold miner Newcrest backs Newmont's $17.8 billion offer

(Adds Newcrest shares opening)

By Scott Murdoch and Melanie Burton

SYDNEY, May 15 (Reuters) - Australian gold miner Newcrest Mining Ltd said on Monday it would back Newmont Corp's A$26.2 billion ($17.8 billion) takeover offer in one of the world's largest buyouts so far this year.

The deal, subject to approval from shareholders of both companies and other regulatory hurdles, would lift Newmont's gold output to nearly double its nearest rival, Barrick Gold Corp, and catapult the miner past Freeport McMoRan to become the largest U.S. gold and copper producer by market capitalisation.

Newcrest shareholders would receive 0.400 Newmont share for each share held, with an implied value of A$29.27 a share, higher than a previous exchange ratio of 0.380 that Newcrest's board rejected in February.

Newcrest shares opened on Monday 1.5% higher at A$28.68, and the offer is a 30.4% premium to the stock's price in February before the Newmont bid became public.

Newmont is also allowing Newcrest to pay a franked special dividend of up to $1.10 per share on the implementation of the deal that returns tax credits to Australian shareholders.

The merger is set to be the third-largest deal ever involving an Australian company and the third-largest globally in 2023, according to data from Refinitiv and Reuters' calculations.

"This transaction will combine two of the world's leading gold producers, bringing forward significant value to Newcrest shareholders through the recognition of our outstanding growth pipeline," said Newcrest Chairman Peter Tomsett.

Newmont said it would have about 8 million ounces of total combined annual gold production once the deal closed, with more than 5 million gold ounces from 10 long-life and low-cost mines.

The Denver-based miner added it would have combined annual copper production of approximately 350 million pounds from Australia and Canada.

Newcrest shareholders will be able to choose to receive New York Stock Exchange-listed Newmont shares or Australian-listed CHESS Depository Instruments (CDIs) as payment.

Newcrest said it recommended its shareholders vote in favour of the deal at a meeting expected to be held in September or October.

The deal requires Australia's Foreign Investment Review Board (FIRB) approval as well as Newcrest and Newmont shareholders to vote in support the transaction, among other regulatory requirements.

The companies said the deal was due to be finalised in the fourth quarter of 2023.

($1 = 1.4743 Australian dollars) (Reporting by Scott Murdoch in Sydney, Melanie Burton in Melbourne and Himanshi Akhand in Bengaluru; Editing by Lisa Shumaker, Cynthia Osterman and Jamie Freed)