Wal-Mart has agreed to pay $11 million to settle a lawsuit that alleged it used illegal immigrants as janitors to clean its stores.

Two investigations were conducted which found that 345 immigrants from 18 different countries were hired by the retail giant as janitors at stores all across the United States.

In addition, the probes determined that the immigrants often worked seven days a week and did not receive overtime pay. Many workers who were on the overnight shift were locked in the stores until the following morning.

While the investigations found that Wal-Mart did not directly hire the immigrant workers, it did reveal that the company's executives were aware that the third party contractor they hired the janitors through was using illegals to work at Wal-Mart stores.

Tom Mars, Wal-Mart's general counsel released a statement indicating, 'Today we are acknowledging that our compliance program did not include all the procedures necessary to identify independent floor cleaning contractors who did not comply with federal immigration laws. We will use this as an opportunity to improve and be a better, more tightly run business as a result.'

In addition, Wal-Mart announced it was reviewing how it hires third-party contractors to provide services for its stores.