Wal-Mart: Did not find out which subcontractors used illegal labour

The workers were employed as janitors and cleaners by subcontractors to work in Wal-Mart stores.

The issue came to light in an October 2003 probe at 60 Wal-Mart stores.

Wal-Mart, which owns the UK's Asda chain, said the government would not pursue any criminal charges against the firm or any of its employees.

"Today we are acknowledging that our compliance programme did not include all the procedures necessary to identify independent floor cleaning contractors who did not comply with federal immigration laws," Tom Mars, Wal-Mart's general counsel, said in the statement.

In February the company reported a 16% climb in quarterly profits, boosted by international sales and the expansion of its store network.