( KTRS ) U.S. Steel will temporarily idle its Granite City Works steelmaking and finishing operations, putting about 2,000 workers off the job indefinitely.

The steelmaker did not indicate how long the shutdown would last in a two-paragraph announcement Monday afternoon.

The company says the shutdown is the result of market conditions including fluctuating oil prices, reduced rig counts, imports and depressed steel prices. Most steel produced at the southern Illinois mill is shipped to a Texas plant that turns it into pipe for the oil and gas industry. Earlier this year, U.S. Steel said it would close two Granite City coke ovens and cut 176 jobs. A company spokeswoman said the ovens were more than 30 years old and inefficient.

The mill was completely idled for six months beginning in December 2008.