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Feb 9 (Reuters) - Asia Resource Minerals Plc said it would raise $100 million through a share issue at 25 pence each, a 79 percent premium to the stock's closing price on Friday, and would be underwritten by a trust of Nat Rothschild.
Shares in the Indonesia-focused coal miner, formerly known as Bumi, rose as much as 64.3 percent on Monday, touching a high of 23 pence on the London Stock Exchange.
Rothschild set up Bumi with Indonesia's prominent Bakrie family in 2010. The company's market value plummeted, dragged down by falling coal prices and bitter boardroom battles.
Rothschild, the second-largest shareholder in ARMS with an about 18 percent stake, offered in November to raise his stake, proposing to underwrite a share sale to help cut debt.
The group, with a market value of about $51 million, has a total debt of about $1 billion.
If the shares are not fully subscribed, Rothschild's beneficial ownership interest would rise and the company will enter into a new relationship agreement with Rothschild and the trust NR Holdings, ARMS said.
The company also said it would talk to its bondholders to extend the maturity of both $450 million notes due July 2015 and $500 million notes due July 2017.
Shares in the company rose 50 percent to 21.13 pence at 0843 GMT. They have plunged about 97 percent in value until Friday since touching a record high in April 2011. (Reporting by Aastha Agnihotri in Bengaluru; Editing by Gopakumar Warrier)