By Praveen Menon and Shashwat Awasthi
(Reuters) -Rio Tinto on Thursday reached an agreement in principle to buy the rest of Canada's Turquoise Hill Resources for $3.3 billion which will give the global miner direct ownership of a giant copper mine in Mongolia.
Rio will pay C$43 per share in cash for the 49% of Turquoise Hill it does not already own, a more than 19% premium to the stock's last close and higher than a sweetened offer of C$40 proposed last month.
An independent committee, appointed by Turquoise Hill to determine if the offer was in the best interests of minority shareholders, indicated the "fair market value... is in the range of C$42 to C$58 per common share."
The deal, which awaits shareholder approval, would give Rio Tinto a 66% stake in Oyu Tolgoi, the world's largest known copper and gold deposits, which sits 550 km (342 miles) south of Mongolia's capital Ulaanbaatar.
Copper is set for strong demand from growth in electric vehicles, their charging stations and other renewable energy infrastructure, as the world gears up to decarbonise.
The takeover process has been underway for about six months with Turquoise Hill earlier rejecting an offer of C$34 from Rio as too low.
"This agreement ... will simplify governance, improve efficiency and create greater certainty of funding for the long-term success of the Oyu Tolgoi project," Rio Tinto Chief Executive Officer Jakob Stausholm said.
Rio and the Mongolian government, which owns the remaining 34% of Oyu Tolgoi, earlier this year ended a long-running dispute on costs for a $7-billion underground expansion of the mine which should start production in 2023.
U.S.-listed shares of Turquoise Hill rose 13% in premarket trade. Rio shares were down 3.5% in London.
Rio rival BHP Group was rebuffed in its A$8.34 billion ($5.8 billion) takeover bid for OZ Minerals last month as it looks to shift into clean energy and the EVs market.
BHP has not said if it will sweeten its offer.
Rio and Turquoise Hill said they had also agreed to amend financing arrangements to help the Canadian firm address near-term liquidity, including increasing a May advance facility to $650 million from $400 million and extending the deadline for a $650 million equity raising and debt repayment to at least March 2023.
The amended arrangements also include a commitment by Rio to participate pro rata in an initial equity offering.
A special meeting of Turquoise Hill shareholders to approve the deal is expected in the fourth quarter and the deal, if approved, will close shortly thereafter, Rio said.
"We think that C$43 is an attractive offer, we've had engagement with some of the shareholders and they found it attractive," Bold Baatar, head of Rio's copper business, told Reuters.
"OT is still a project in construction that needs long-term capital funding that makes it very difficult to match against current share price fluctuations."
($1 = 1.4669 Australian dollars)
(Reporting by Shashwat Awasthi, Praveen Menon, Clara Denina; editing by Sherry Jacob-Phillips and Jason Neely)