SINGAPORE, Oct 11 (Reuters) - The directors of troubled Bumi Plc , one of the world's largest thermal coal exporters, hold a board meeting on Thursday as the future of the company created by British financier Nat Rothschild and Indonesia's Bakrie family hangs in the balance.
Allegations of impropriety, against a background of weak coal prices and tumbling shares, have strained already frayed relations between major investors in the London venture and fuelled speculation of a potential split.
The relationship between Rothschild and the Bakries, one of Indonesia's most powerful and politically-connected families, has soured over the past year, particularly after a leaked letter from the financier last November that called for a "radical clean-up". Rothschild was removed as co-chairman months later.
Relations have also frayed between the Bakries and Indonesian tycoon Samin Tan, who pulled the Bakries back from default last year with a $1 billion investment, only to watch the value of his shares crumble.
The Bakries and Tan each hold half of a 47.6 percent stake in Bumi Plc, while Rothschild owns 12 percent.
Sources have said Tan is "furious" with the Bakries after watching the value of his investment plunge -- the shares he bought are worth 9 times less than the level at which he came in.
The board meeting is in Singapore, and is the first gathering since an inquiry into potential wrongdoing at the group's Indonesian operations was announced last month.
The independent probe, being led by a London law firm and still in progress, has revived worries over governance at Bumi Plc and concerns over the woes of its debt-burdened affiliate, PT Bumi Resources , the jewel in the Bakrie empire.
Heightening tensions before the Singapore meeting, the Bakries said on Wednesday that telephones and e-mail accounts belonging to the family and its group of companies had been hacked, pointing to unspecified "suspicions" over who to blame. The incident has been reported to Indonesian police.
Most of the allegations of impropriety, expected to total more than $500 million, relate to Bumi Resources, the flagship Bakrie miner and Indonesia's largest coal producer. Two of three investments at the centre of the probe, though, have already been written down to zero by the London parent.
"While we are not able to quantify the amounts involved in these irregularities, we believe this investigation may reinforce the idea that the company needs to address its complex corporate structure," analysts at JP Morgan, the bank that fostered the creation of Bumi, said in a note last month.
Sources familiar with the matter said Thursday's board meeting was a scheduled gathering, with a long-planned to-do list - but top of the agenda will be progress made by lawyers on their probe, which could run into next month.
The meeting of the board members, 16 after the resignation of former CEO Ari Hudaya, is expected to include Chairman Samin Tan, co-Chairman Indra Bakrie and Rothschild, and is therefore unlikely to escape discussion on the future of the group.
At least one of the sources, though, said no restructuring could be decided before the full investigation was completed.
Bumi Plc has long said it would like to bring together Bumi Resources, in which it owns 29 percent, and coal miner Berau, in which it owns 85 percent, into a single operating holding.
But options being considered by teams of advisers courting Bumi in recent weeks include more radical solutions, such as a divorce of Bumi Resources from the group.
Bumi Plc's board could also seek to replace Hudaya, who was chief executive until March and is still chief executive of Bumi Resources.
Two sources also said they could not exclude other changes.
(Reporting by Janeman Latul and Clara Ferreira-Marques in LONDON; Editing by Raju Gopalakrishnan)