UPDATE 2-Brazil's oil firm OGX presses Batista for cash; shares soar
* OGX calls on Batista for immediate $100 mln
* OGX to exercise part of $1 bln put sold by Batista
* Unclear how Batista will generate the cash
* OGX shares up nearly 30 pct in afternoon
(Adds details on Ternium, details on Batista, updates share price)
SAO PAULO, Sept 6 (Reuters) - Brazil's debt-laden oil company OGX said on Friday it has called in a promise from controlling stakeholder Eike Batista to start injecting $1 billion into his empire's flagship company while it renegotiates debt.
Once the crown jewel of Batista's multibillion-dollar energy, shipbuilding and mining empire, OGX Petróleo e Gás Participações SA said in a filing on Friday it would take $100 million immediately, prompting shares to surge nearly 30 percent.
The move is the latest twist in the unraveling empire of Batista, who once ranked as the world's seventh-richest person but whose worth is now less than $900 million, according to Forbes magazine.
In an attempt to shore up declining confidence in OGX in October 2012, Batista pledged to put up $1 billion in the form of a financial guarantee called a put option to be exercised at the discretion of the board.
How he will generate the cash to make good on the entire OGX put option, as well as other promises to inject cash into his foundering empire, is still unclear.
Over the past week, in five separate sales of stock, Batista trimmed his controlling stake in OGX to about 52 percent to generate cash and avert bankruptcy.
Creditors have been pressuring Batista to fulfill his promise to inject cash into OGX through the option that allows the company to sell $1 billion of stock to Batista at 6.30 reais a share by April 30, 2014, if needed.
Company shares, which closed at 0.41 reais on Thursday, were trading up 29.3 percent at 0.53 reais on Friday afternoon. OGX bonds were also rallying.
The option is seen as a last-ditch effort to keep OGX afloat after it burned through cash faster than many analysts expected and would-be investor, Malaysian oil company Petronas, got cold feet as doubts over OGX's solvency surfaced.
Batista is in talks with his main debt holders, including PIMCO and BlackRock, to convert $3.6 billion in notes to equity and inject up to $500 million in fresh capital to avert the company's entering bankruptcy protection.
In a similar exercise by one of Batista's companies on Wednesday, the board of shipbuilder OSX Brasil SA said it will exercise a put option with Batista at a value of up to $50 million.
In another sign of instability in Batista's empire, steelmaker Ternium SA said on Friday it would halt plans to build a plant at the Açu Port project, owned by the formerly Batista-controlled logistics company LLX SA.
(Reporting by Reese Ewing; editing by Gerald E. McCormick, Nick Zieminski and Matthew Lewis)