Hershey Co., producer of Reese's chocolate candies, has filed a lawsuit against Mars Inc., complaining that the wrapping of the latter's Dove line of peanut butter and chocolate bars copy its packaging.

The lawsuit filed in the federal district court of Pennsylvania last week complains that Mars, the maker of Snickers and M&Ms, has packaged the Dove peanut butter chocolate Promise squares in such a way that it mimics the patented orange, brown and tan wrappings of the Reese's peanut butter chocolate products that Hershey has marketed for decades.

The use of the colors is an attempt to trade on Hershey's goodwill and to confuse consumers as to the origin, source or sponsorship of defendant's product, Hershey said in its complaint. The company is claiming trademark dilution and infringement, and unfair competition against the McLean, Virginia-based Mars.

However, Mars has responded by counter-suing Hershey in the federal district court of Virginia and saying that orange is commonly used by third parties on packaging as a generic flavor designation for peanuts, peanut butter or peanut butter flavoring.

This is not the first time Hershey and Mars have locked horns. Two years back, Mars subtly attacked Hershey over its cost-cutting moves, which included shutting down three of its U.S. plants and blending cocoa butter substitutes into some of its chocolate candy sold in the domestic market, by advertising that Dove was made in the USA of 'pure, rich chocolate.

Last year, Mars also sued Hershey over commercials for its Bliss chocolate that Mars claims blatantly copy television ads for its premium Dove chocolate brand.

Hershey is the largest maker of chocolate candies in the U.S. It was also larger than Mars in the confectionery segment. However, in 2008, Mars vaulted past Hershey with its $23 billion acquisition of mint and chewing gum giant William Wrigley Jr. Co.