UPDATE 1-Indonesia's Bumi raises share buyback size

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JAKARTA, June 10 (Reuters) - Indonesia's largest coal miner, PT Bumi Resources Tbk (BUMI.JK), raised on Tuesday the size of a planned buyback to 3 percent of its share capital, worth up to $725.3 million at a maximum share price of 11,600 rupiah ($1.25).

The company had said last month it would only buy back up to 1 percent of its share capital, as part of moves to return cash to shareholders and support its share price.

Bumi said in a statement on Tuesday it would purchase up to 582.12 million shares at a maximum price of 11,600 rupiah each, well above Monday's closing price of 8,450 rupiah.

The company, controlled by the family of Indonesia's chief social welfare minister Aburizal Bakrie through holding company PT Bakrie & Brothers Tbk (BNBR.JK), has become the largest capitalised firm in Indonesia, overtaking PT Telekomunikasi Indonesia Tbk (TLKM.JK).

Bumi shares jumped nearly 7 percent on Monday after it announced the discovery of an additional 442 million tonnes of coal reserves in Borneo island, which will raise its marketable reserves by nearly a third.

Since the start of the year, Bumi's shares have risen by more than 40 percent, outpacing a 12 percent drop in the Indonesia Stock Exchange composite index .JKSE. ($1=9,310 rupiah) (Reporting by Harry Suhartono and Tyagita Silka, editing by Ed Davies)