Coca-Cola claimed artist Haddon Sundblom created Santa's image for the brand; it debuted in a 1931 print ad in US titles including National Geographic.
But US company White Rock said it used a fat, white-whiskered red- and white-clad Santa in newspaper and magazine ads as early as 1915.
Larry Bodkin, president of White Rock Beverages, said: 'For Coke to perpetuate this myth for so long is abominable. It has co-opted Claus and it wouldn't surprise me to hear it was trying to claim it created the Easter Bunny too.'
Although the red-and-white-suited, bearded Santa is the most widely recognised image, over the centuries he has been depicted as everything from an elf to a tall, gaunt man.