Wal-Mart Stores Inc. (WMT) said Thursday it is expanding its $4 generic prescription program to 11 additional states and adding 17 more prescriptions to the program.

The world's largest retailer added 502 stores to those offering the discounted medications. The new states added Thursday were Idaho, Kentucky, Maine, Massachusetts, Nebraska, Oklahoma, Rhode Island, South Carolina, Utah, Washington and West Virginia. In all, Wal-Mart is offering the program in 3,009 stores in 38 states.

The $4 price is for up to a 30-day supply of the drugs, which will now number 331. That number counts some drugs more than once if they are sold in a variety of dosages or solid and liquid forms.

The company began the program in September, offering the low-cost drugs in Florida and had plans to expand the offering in January. But the company said it moved up its timetable.

Wal-Mart launched the program in what it called an effort to save working Americans money on health care. Critics said it was a stunt to draw in business and a grab for a bigger share of the drug business.

Other states under the program are: Alabama, Alaska, Arizona, Arkansas, Delaware, Georgia, Illinois, Indiana, Iowa, Kansas, Maryland, Michigan, Mississippi, Missouri, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, Ohio, Oregon, South Dakota, Texas, Vermont and Virginia.

Wal-Mart said it intends to continue to push for expansion to other states as quickly as possible.