Tensions are rising in a marketing dispute between Verizon (VZ -1.5%) and Comcast (CMCSA -0.2%), as Verizon's refusal to deal with the National Advertising Division means the dispute is being punted to the FTC and FCC.

Comcast has balked at a number of Verizon's claims about FiOS Internet speeds (such as "Only FiOS has the Fastest Internet Available") and challenged them via a proceeding at the NAD -- but Verizon has declined to participate, saying NAD has a conflict of interest.

"We've participated in countless NAD matters over the years and have never before encountered a situation requiring the company to decline to participate in this voluntary self-regulatory process," Verizon says in a statement.

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