UPDATE 1-Sumitomo Metal, China Steel plan Vietnam jv

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TOKYO, Dec 20 (Reuters) - Sumitomo Metal Industries Ltd (5405.T), Japan's third-biggest steel maker, and its Taiwanese partner China Steel Corp (2002.TW) said on Thursday they plan to form a joint venture to produce steel plate in Vietnam.

The total investment will exceed $1 billion, the Japanese company said.

The new company will start operating in 2011, with facilities capable of producing 1.7 million tonnes a year of cold-rolled steel, used in consumer electronics, and electric steel sheet used in motors, among others.

Other details have not been decided, a company spokesman said.

Sumitomo Metal Industries and China Steel jointly own an upstream joint venture at Sumitomo's Wakayama works in Japan. The partnership and the venture, formed in 2003, have resulted in higher operations at the plant and a tighter market in Japan.

China Steel in August agreed to take a 15 percent stake in Sumitomo Metal's steel processing centre in Thailand. Sumitomo Metal then said it would take a stake in China Steel's planned Vietnamese venture.

(Reporting by Yuko Inoue)