General Motors' West Mifflin stamping plant will remain open only until the company is able to move the equipment to other facilities -- although it's unknown how long that process will take, GM officials said yesterday.

News of the closing came after it was announced that a deal to sell the plant to Allegheny Holdings had fallen through when a line of credit expired. One of Allegheny Holding's leaders is retired GM executive Thomas Brady.

"Talks between General Motors and Allegheny Holdings regarding the sale of GM's Pittsburgh Metal Stamping Plant have ended unsuccessfully," said GM spokesman Dan Flores.

"The plant will now remain a GM facility for an unspecified period of time until work is either moved or reaches the end of its life cycle, at which time the plant will close."

The plant's roughly 350 maintenance and production workers, who are represented by United Auto Workers Local 544, have been through a series of ups and downs that began in November 2006 when the automaker announced that the West Mifflin facility would be closing in 2007.

But that closing was postponed while talks were under way on selling the plant to Allegheny Holdings.

GM officials met with the workers yesterday after the deal fell through to explain what had happened in the now failed talks. Union officials could not be reached for comment.

For its part, Allegheny Holdings says on its Web site that the senior lender on the proposal would not continue the terms of the original commitment when it expired March 28.

"There's understandably going to be a lot of rumors and speculation about what may or may not happen in the future. But we are not in a position to speculate on what will happen to the facility after the plant closes," Mr. Flores said.

Others who are familiar with the situation say that GM, which has a reputation for trying to find alternative uses for facilities it has closed, would entertain other options, including any other buyers who would step forward. But for now, no such buyer has surfaced.

If the plant does close, laid-off workers will receive the same benefits and assistance that were agreed to in the national contract with General Motors, which was ratified in October. They would be offered transfers to other facilities and help with relocation, or they could exercise other options spelled out in the contract.