UPDATE 1-Thai Banpu to buy rest of China coal miner

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BANGKOK, June 6 (Reuters) - Banpu BANP.BK, Thailand's biggest coal miner, said on Friday it planned to spend $420 million for a remaining 78.40 percent stake in a Chinese coal miner.

The acquisition by Banpu's wholly-owned unit, BP Overseas Development Co Ltd, would take its stake to 100 percent in Asian American Coal Inc (AACI), the company said in a statement.

AACI holds a 56 percent stake in Shanxi Asian American-Daning Energy Co. Ltd, which has a 25-year concession with estimated coal reserves of 88 million tonnes in the northern province of Shanxi.

AACI also holds 45 percent of Shanxi Gaohe Energy Co Ltd., which has a 30-year concession to develop a underground mine with 191 million tonnes of coal reserves, the statement said.

At 0804 GMT, shares in Banpu were up 3.42 percent at 484 baht, while the overall Thai market .SETI was 1.01 percent higher. ($1=33.08 Baht) (Reporting by Arada Therdthammakun; Editing by Darren Schuettler)