Bosch cut 600 jobs at its Miskin plant late in 2008
Further job losses are feared at a Bosch car parts factory after figures showed sales fell 45% in the past year.
The 900 workers at Miskin, Rhondda Cynon Taf, have been told redundancies are likely and closure has not been ruled out if demand continues to drop.
Last year, 600 contracted and agency staff were laid off at the plant.
The Welsh Assembly Government said officials would meet senior management from Bosch next week to discuss the possibility of supporting the plant.
Bosch, which has made alternators at the plant near Llantrisant since 1991, is seen as a jewel in the Welsh automotive industry.
Workers make the electrical generating devices for luxury cars, but the company says the bottom has fallen out of the market.
Sales have dropped 45% this year and are predicted to drop 65% in 2010.
The company issued a statement after managers held talks with staff on the night shift.
It said managers would have to establish whether they would be "forced to enter into consultations on further employment risks".
The statement added: "This comes after months of difficulty for the plant and in recent years, generator production... has failed to meet its financial targets."
A number of outcomes will now be discussed with staff. The firm admits that redundancies are the most likely.
Managers held meetings with the staff council on Thursday night.
An assembly government spokesman said: "Assembly government officials are in close contact with Bosch.
"A meeting with the plant's senior management has already been arranged for early next week to discuss in detail the challenges facing the operation and to explore any potential means by which the assembly government could support the company's Welsh operation."
Chris Franks, a Plaid Cymru AM for South Wales Central, said the news was "very worrying".
He said: "Unlike previous recessions in the 1980s and 1990s when Wales was defenceless, we have a Welsh assembly and a government that will not sacrifice our own people as we fight the ravages of the world's financial crisis.
"I have written to local councils to ask them to give this a top priority."
Welsh Conservative industry spokesman Alun Cairns said the news "highlights once again the fragility of the Welsh economy in the face of a global recession".
He added that it was important for the assembly government to work with Bosch to secure investment and to broaden the plant's productivity base.