General Motors Corp said on Thursday that 7,500 workers -- or about 12 percent of its U.S. factory workforce -- represented by the United Auto Workers union had accepted buyout offers to leave the struggling automaker's payroll.

About 90 percent of the workers who took the buyout of $20,000 cash and a $25,000 vehicle voucher were eligible to immediately retire, GM spokesman Tony Sapienza said.

The announcement came less than a week before GM and its smaller rival Chrysler LLC are due to hear back from U.S. officials on a request for additional emergency loans to help them ride out the weakest auto sales in three decades.

Both automakers have won pending contract changes from the UAW intended to help them cut costs to the level of Japanese automakers operating plants in the United States.

GM and Chrysler are both also still working to complete related deals with the UAW that would allow them to pay the union in stock rather than cash for remaining obligations to a trust fund for retiree health care.

Separately, Chrysler said it was extending the deadline for its UAW workers to accept buyouts and early retirement incentives for the second time since the program was offered in early February.

Chrysler, which is owned by private equity firm Cerberus Capital Management , declined to detail how many UAW-represented workers had taken its buyout offer so far.

The two automakers have taken $13.4 billion in loans from the U.S. Treasury to date and asked for another $20 billion in combined funding in a request that hinges on their ability to win concessions from the union and creditors.

GM cut 34,000 UAW-represented factory jobs in 2006 and another 19,000 in 2008 through buyouts and early retirement incentives.

Including the latest round of buyouts, the struggling automaker has cut 60,500 jobs -- or more than half of its U.S. factory work force -- over the past three years as U.S. auto sales have slowed and its own cash position has weakened.

GM said it would replace retiring workers with existing workers wherever possible. The automaker said that where it had to hire new workers, those hires would be made at a new entry-level wage negotiated in 2007 with the UAW.

That would allow GM to hire the new workers at a wage of $14 per hour, roughly half of the prevailing wage for current assembly line workers.

(Editing by Matthew Lewis)