UPDATE 2-Sibir market value halves on real estate buy

* To buy more real estate assets from one of its top owners

* Deal to cost co $127 mln in cash, $213 mln in debt

* Co says move designed to preserve shareholder structure

* Stock sinks 55 pct

* FD resigns

(Adds fund manager, details, updates share price)

By Dmitry Zhdannikov and Gleb Bryanski

MOSCOW, Dec 3 (Reuters) - The market value of London-listed Sibir Energy SBE.L halved on Wednesday after the Russian oil firm said it would buy more distressed real estate assets from its key owner for $340 million in cash and debt.

Sibir had already outraged minority shareholders when it said in October it would buy some $157 million worth of real estate from its key owner, Russian businessman Shalva Chigirinsky, in a clear departure from its core oil business.

The new deal foresees the purchase of various real estate assets including Russia Tower, a 6OO-metre (1,970 foot) steel-and-glass symbol of new Russian wealth designed by Norman Foster to be Europe's tallest building, which was halted last month due to a lack of funding. [ID:nLL584465]

"This is a corporate scandal of the first class," said Carl Merling, CEO of Swedish hedge fund Emeralt Investments, which has a big exposure to Russia but holds no Sibir shares.

"It is difficult in such a situation not to be negative towards Russian small caps with majority owners like Chigirinsky. When such things happen there is no mechanism for minority shareholders to protect their rights," he said.

Sibir asked the shareholders to approve the purchase of additional real estate assets from Chigirinsky, spelt Tchigirinski by the company, at a general meeting on Dec. 18.

"Difficult times call for uncomfortable decisions to be made," Sibir Chief Executive Henry Cameron said in a statement.

"Doing business in Russia has never been for the faint-hearted and sometimes requires difficult calls in the boardroom," he added.

The company said the global financial crisis and consequential drop in share values have had "a domino effect" on Chigirinsky's financial position.

Chigirinsky and his partner Igor Kesayev control 47 percent of Sibir and the government of Moscow owns another 18 percent.

The company produces oil in West Siberia and has a refinery and a petrol station network in Moscow.

Most of the projects that Sibir will acquire from Chigirinsky have been put on ice like many other real estate developments in Russia. Heavily indebted developers have been among the worst hit by the global liquidity squeeze.

The company said it will nevertheless have to spend $128 million on limited development and studies of some of the projects, including New Holland and Passage in St Petersburg, thus taking the sum of Sibir's support to $625 million.

Sibir had a net profit of $238.5 million in the first half of 2008.

Sibir has earlier denied reports that Chigirinsky and Kesayev could lose their stakes in the company after local media reported the businessmen were facing margin calls after putting their stakes in Sibir as collateral against bank loans.

"As the preservation of the company's shareholder structure was paramount, the board of Sibir has concluded that the company must take over the bulk of Mr Tchigirinski's remaining real estate business," the company said on Wednesday.

Sibir said in a separate statement its finance director and member of the board, Alexander Betsky, resigned on Tuesday.

At 1050 GMT, Sibir was trading at 45.025 pence, down 55 percent on the day. (Reporting by Dmitry Zhdannikov; editing by Simon Jessop)