Two more staffing providers were sued this month by warehouse workers claiming the firms paid them less than the minimum wage. The two firms, Eclipse Advantage Inc. and Midwest Temp Group Inc., provide workers at a warehouse in Elwood, Ill., that provides goods to Wal-Mart Stores Inc., according to the lawsuit.

This is the second suit filed this month against warehouse staffing firms. The other lawsuit was filed against two staffing providers at warehouses in Southern California.

In the Illinois lawsuit, workers claim the staffing firms provided either no information or incorrect information on pay stubs and didn’t pay minimum wage for all hours worked. In addition, the suit claims the firms did not pay the minimum of four hours’ “show up pay” when workers were called in but not utilized for a full four hours. The suit also alleges that vacation pay earned was not paid.

"The Midwest Group always has and always will pay its workers fairly and in accordance with all labor laws," said Pam Valy, president of The Midwest Group. "This lawsuit is a union stunt to embarrass the most successful company in the country. We are pleased to provide employment to thousands of individuals in a difficult economy and help contribute to the success of Wal-Mart, which is the real target of this suit."

The Illinois suit is seeking class action status. Only Eclipse Advantage and MidWest Temp Group are named as defendants in the suit. Wal-Mart is not named as a defendant.

The lawsuit was filed in U.S. District Court in Illinois.