UPDATE 1-Chinalco belief in metals cycle behind Rio stake

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LONDON, Feb 1 (Reuters) - A bullish view of the metals cycle was a driving factor behind Aluminum Corp of China's (Chinalco) move to team up with U.S. Alcoa (AA.N: Quote, Profile, Research) to buy a stake in mining group Rio Tinto (RIO.L: Quote, Profile, Research), the head of Chinalco said on Friday.

"We made this investment primarily because of... our strong belief in the sustained strength of the commodity cycle," Chinalco President Xiao Yaqing told a news conference in London.

"We have a very bullish view on the long-term prospects of the global mining sector," he added.

Chinalco announced on Friday it had teamed up with Alcoa to buy a $14 billion stake in Rio Tinto, accounting for 9 percent of Rio's total shares listed in the UK and Australia.

The move by state-owned Chinalco is the China's biggest ever investment overseas, with Alcoa spending only $1.2 billion for its participation.

The move comes days before a regulatory deadline on Wednesday for BHP Billiton (BLT.L: Quote, Profile, Research) to make a firm offer for Rio (RIO.AX: Quote, Profile, Research) or walk away, but Xiao said Chinalco's motive was to diversify into an international metals and mining group.

Chinese steel companies have opposed BHP's plans to acquire Rio since a marriage of the two firms would create a massive controlling force across a range of commodities such as iron ore and coal.

But Xiao said concern for China's role as a huge consumer of commodities was not a major impetus for his firm's move, rather it was the group's long-term view of the commodities sector within an increasingly globalised economy.