ASHLAND, Ky. — The AK Steel plant in Ashland, Ky., is being “idled,” leaving in excess of 600 workers out of a job, a union leader and corporate officials confirmed Tuesday afternoon.

Officials with AK Steel Holding Corp. said the facility in Ashland and one in Mansfield will remain idle until early to mid-January because of economic turmoil that has sharply lowered demand for its steel products.

‘‘We remain hopeful that we will be able to return our dedicated and hardworking employees to their jobs as swiftly as possible,’’ James L. Wainscott, AK Steel’s chairman, president and chief executive, said in a prepared statement. ‘‘Of course, that depends entirely on credit availability and consumer confidence, which are at the heart of this serious economic downturn.’’

Officials with the company said they will continue to evaluate operations in light of the downturn, and will be prepared to restart the idled facilities sooner than planned if business conditions improve.

AK Steel halted steel production and shipping earlier this week at the Mansfield plant, which employs 365 people and makes flat-rolled steel used mainly in automotive exhaust systems. A small number of workers will continue to maintain the plant.

Mike Hewlett, president of the United Steelworkers Union 1865, said he was told the Ashland employees would be laid off Nov. 22 but a small number of employees will remain at the Ashland plant, which makes flat-rolled steel used in autos and appliances, to prepare for a restart. Hewlett said AK Steel corporate executives advised him of the development during a 2 p.m. meeting Tuesday afternoon.

“The economy is shot to pieces right now,” Hewlett said. “We’ve got to deal with the leftovers of George W. Bush. We’re hoping there are things we can do. It depends on what they send us.”

Hewlett said various departments within the steel plant have been shut down in the past, as recently as the 1990s, but none of the previous activity was as serious and involved as many people as this latest one.

The company’s agreement with union workers includes funding that would supplement state unemployment compensation.

Last week, AK Steel slashed its projected fourth-quarter steel shipments by about 14 percent, citing weaker-than-expected U.S. and global economic conditions.

The company said it expects shipments to be closer to 1.2 million tons than the 1.4 million tons forecast when the company reported a jump in third-quarter profit last month.

Shares of AK Steel fell 72 cents, or 6.5 percent, to $10.31 on Tuesday.