NEW YORK (CNN/Money) - Comcast Corp. raised the ire of several consumer groups after the No. 1 cable company boosted Internet access fees by 33 percent for those customers who do not also subscribe to its cable television service, according to a published report Wednesday.

The Consumes Union and the Consumer Federation of America have asked the Justice Department and the Federal Trade Commission to investigate whether the company violated antitrust laws by raising the Web-only access fee to $57 per month, $14 more than subscribers who also order cable TV, USA Today reported.

Comcast said it competes with satellite services firms that offer Internet access and phone companies that offer digital subscriber line services. "Where there's competition, people look for discounts," company spokeswoman Sarah Eder told the paper.

Gene Kimmelman of the Consumers Union suggested that Comcast's pricing is predatory, with TV subscribers paying below market rates for Internet service. Once rival satellite television providers lose subscribers in the price battle, the cable operators could "jack prices up above market costs," he told USA Today.

When asked what it costs to provide Internet service, Comcast's Eder told the paper the company has never talked about specific costs.

Shares of Comcast (CMCSA: Research, Estimates) rose 66 cents Tuesday to close at $29.25.