Bentonville-based Wal-Mart said today it has received a "target letter" from the US Attorney`s Office saying the world`s largest retailer allegedly violated federal immigration laws. Wal-Mart spokeswoman Mona Williams says the company is the target and no Wal-Mart employee has yet received an individual letter. On October 23rd, federal agents arrested about 250 allegedly illegal workers in a 21-state sweep of 60 Wal-Mart stores. The raids focused on floor cleaners employed by companies Wal-Mart hired for the work. Ten of those arrested were Wal-Mart employees hired as the company moved to bring its floor cleaning in-house. Wal-Mart received the letter Friday. Williams says the grand jury will look at whether the company -- quote -- "violated federal immigration laws in connection with the use of third-party floor cleaning contractors." Williams says the company was not surprised by the letter and is cooperating with the government. The company expects the grand jury to begin its hearing in mid-December. Assistant U.S. Attorney Wayne Samuelson in Williamsport, Pennsylvania, where the case is being handled, would not discuss case specifics.