SOUTH MILWAUKEE, Wis. — Caterpillar Inc. says it is placing about 260 production employees at its South Milwaukee plant on indefinite layoff because of weaker demand for mining equipment.

The layoffs represent about a third of the more than 800 workers represented by the Steelworkers union at the plant. The layoffs go into effect June 24.

The Milwaukee Journal Sentinel (http://bit.ly/15491Y5) reports the layoff notices come just three days after members of United Steelworkers Local 1343 ratified a six-year labor contract.

Caterpillar says the Peoria, Ill.-based company earlier announced plans to lay off production employees at the plant. The company says customer orders for mining equipment made at the plant are weaker than they were a year ago.

Caterpillar says the layoffs will bring production in line with demand.