SYDNEY, Australia – Global mining company BHP Billiton said Thursday that U.S. antitrust regulators had granted partial approval for its $170 billion hostile takeover bid for rival Rio Tinto.

BHP Billiton Ltd., the world's largest mining company, said the U.S. Department of Justice and the U.S. Federal Trade Commission had ended antitrust waiting period on the proposed deal early. The waiting period, under the Hart-Scott-Rodino Act, is used to determine if a takeover violates antitrust laws.

The Justice Department's antitrust division has also concluded a review of the proposal without further action, the company said.

“We are very pleased that we have received notice of early termination of the Hart-Scott-Rodino Act waiting period and completion of the Department of Justice merger review,” BHP Billiton's chief commercial officer Alberto Calderón said in a statement.

The end of the waiting period satisfied part of U.S. preconditions for clearing the proposed deal, BHP Billiton said.

BHP Billiton is offering 3.4 of its shares for each Rio Tinto share, in a deal worth about $170 billion that would create a megasupplier of iron ore, coal and other resources that are currently in high demand.

Rio Tinto is vigorously resisting the offer.

Clients – notably steelmaking companies in economically booming China – have expressed concerns that a combined BHP Billiton-Rio Tinto company would have too much control over the price of key resources.

The proposal has drawn the attention of regulators in Australia, Europe and the Americas. European Commission and Australian regulators are yet to announce their decisions.