(Reuters) - Warren Buffett’s favorite ice cream company has kicked up a legal storm over the “Blizzard.”

FILE PHOTO - Berkshire Hathaway chairman and CEO Warren Buffett enjoys an ice cream treat from Dairy Queen before the Berkshire Hathaway annual meeting in Omaha, Nebraska, U.S. May 6, 2017. REUTERS/Rick Wilking

American Dairy Queen, whose Blizzard has long been one of its most popular products, sued W.B. Mason Co in federal court this week to stop the office supplies distributor from selling bottled spring water also bearing the Blizzard name.

Dairy Queen’s Blizzard contains soft-serve ice cream that can be blended with fruit, nuts, M&Ms, Oreos and other mix-ins.

W.B. Mason has fought back, and on Thursday filed its own federal lawsuit seeking a declaration that it did not infringe any trademark belonging to Dairy Queen, owned since 1998 by Buffett’s conglomerate, Berkshire Hathaway Inc (BRKa.N).

The litigation is not Dairy Queen’s first over the Blizzard name, and follows its 2010 settlement of a lawsuit involving a Southern California frozen yogurt company, Yogubliz.

Dairy Queen began using the Blizzard name in 1946, and has five Blizzard trademarks dating back to 1952. Its current Blizzard has been for sale since 1985.

W.B. Mason, known for the slogan “Who But W.B. Mason,” has since 2010 sold Blizzard water, in sizes from 8 ounces to 5 gallons, and has used the name to sell copy paper as early as 2003.

It attracted Dairy Queen’s attention last April after submitting trademark applications for Blizzard water.

In its March 12 complaint, Dairy Queen said W.B. Mason’s conduct threatens “irreparable injury” and has caused a “likelihood of confusion” because many of Dairy Queen’s 4,500 U.S. locations sell bottled water.

The Edina, Minnesota-based company, which has more than 6,700 locations worldwide, is seeking an injunction against W.B. Mason, plus profits from water sales.

W.B. Mason, based in Brockton, Massachusetts, said it has “no interest” in creating confusion, and has created none.

The companies have had “a long period of what we call co-existence,” its lawyer, Jason Kravitz, a partner at Nixon Peabody in Boston, said in an interview. “There has not been to our knowledge a single instance of any consumer being confused by W.B. Mason’s sale and promotion of its spring water.”

Dairy Queen does not discuss pending litigation, spokesman Dean Peters said in an email.

Buffett sometimes visits Dairy Queen in his Omaha, Nebraska, hometown.

Known for eating habits that would give some doctors fits, the 87-year-old billionaire told Yahoo Finance in 2016 he usually orders a small sundae for the ice cream and an extra large sundae for the topping, and combines them.

The cases are American Dairy Queen Corp v. W.B. Mason Co, U.S. District Court, District of Minnesota, No. 18-00693; and W.B. Mason Co v American Dairy Queen Corp, U.S. District Court, District of Massachusetts, No. 18-10488.

Reporting by Jonathan Stempel in New York;

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