Wal-Mart is fighting back against a planned walk-out by workers on one of the busiest shopping days of the year.

The United Food and Commercial Workers Union and its subsidiary OUR Wal-Mart are calling for employees to skip work or walk off the job on "Black Friday" -- the traditionally jam-packed shopping tradition the day after Thanksgiving.

Wal-Mart filed a complaint with a federal agency, accusing a labor union of illegally organizing picket lines and other demonstrations.

The planned walkouts build on a small strike at a Los Angeles Wal-Mart in October that spread to 12 other cities.

A Wal-Mart spokesman says the striking workers represent a very small minority of its more than 1 million employees, and that the company is ready for the Black Friday shopping blitz.