Alcoa, Chalco Buy Rio Tinto Stake

It is the largest overseas investment ever by a Chinese company, Aluminum Corp. of China said, and could very well obstruct a bid from Anglo-Australian mining giant BHP Billiton for Rio Tinto.

Alcoa said it contributed $1.2 billion (810 million euros) to the total investment.

Aluminum Corp. of China, the country's biggest maker of both aluminum and alumina, said it made its purchase through a Singapore-based wholly owned unit called Shining Prospect Pte.

The two companies said in a regulatory filing that they did not "currently intend to make an offer for Rio Tinto PLC," though they reserved the right to announce an offer or participate in an offer within the next six months.

"Our acquisition of a significant strategic stake in Rio Tinto PLC today reflects our confidence in the long-term prospects for the rapidly evolving global mining sector," Xiao Yaqing, president of Aluminum Corp. of China, said in a statement.

London-based Rio Tinto became the world's biggest producer of aluminum and bauxite with its $39.7 billion purchase last year of Montreal, Canada-based Alcan.

State-owned Aluminum Corp. of China owns a 38.56 percent stake in listed unit Chalco, whose shares are traded in New York, Hong Kong and Shanghai.

Chalco's shares rose 11.9 percent in Hong Kong on Friday. They fell 2.5 percent in Shanghai, where the market closed before the deal was announced.

Aluminum Corp. of China said its share of the $14.05 billion purchase was partially funded by the China Development Bank, a Beijing-based bank set up mainly to finance government projects.