BHP Billiton

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has increased its hostile stock offer for fellow miner

Rio Tinto

( RTP), upping the ante in its bid to create a mammoth resources firm.

Previously, Australia's BHP had offered three shares for each share of Rio Tinto, but now it says it's raising the proposal to 3.4 shares. The U.K.'s Rio Tinto has thus far refused to negotiate with BHP.

BHP said its stockholders would own 56% of the combined company, and Rio Tinto investors would hold the remaining 44%. Based on BHP's closing price Feb. 4, the offer is worth $147.4 billion, BHP said. That's down from $173.6 billion last fall, when BHP first approached Rio Tinto, because of a decline in its share price.

If Rio Tinto were to accept BHP's new approach and the deal is completed, it would be the latest megamerger to reshape the mining industry in recent years. Among the biggest takeovers have been

Freeport-McMoRan Copper & Gold

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buying Phelps Dodge,

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Companhia Vale do Rio Doce

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acquiring Inco and Rio Tinto purchasing Alcan.

Last week,

Alcoa

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and the

Aluminum Corp. of China

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said they would work together to buy a 12% stake in Rio Tinto.

Separately, BHP reported revenue of $25.54 billion for the six months ended Dec. 31, up 15.5% from the same period in 2006. The company's profit from operations climbed nearly 4% to $9.49 billion from $9.13 billion.

BHP was tacking on 2 cents to $69.50 in after-market trading. Rio Tinto was up 4.4% to $440.05.