A plan to maintain operations at a General Motors plant in eastern France was in doubt after a labor union refused to sign a deal on Friday to freeze salaries and cut working days.

Three other unions agreed to the deal after more than 1,000 of 1,150 workers voted this week to accept conditions set by the Detroit-based carmaker to keep the plant open.

General Motors had said it needed all four unions to agree for it to complete the repurchase of a plant it put up for sale in 2008 to help raise cash and avoid bankruptcy at the height of the financial crisis.

The conditions have not been met. General Motors Strasbourg will inform General Motors Co in the next hours and the headquarters will decide if it will maintain the offer, management of the French subsidiary said.

The Strasbourg factory is under the Motors Liquidation Co, the entity charged with selling off GM's unwanted assets to reduce its debts.

After emerging from bankruptcy in the summer of 2009, GM opted to buy back the plant which produces automatic transmission systems for GM and BMW cars.

On July 16, it offered to repurchase the plant for a symbolic one euro on the condition that costs fell 10 percent.

(Reporting by Gilbert Reilhac; Writing by Bate Felix; Editing by Dan Lalor)

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