WASHINGTON -- The head of the Federal Communications Commission said Thursday he will recommend that the nation's largest cable company be punished for violating agency principles that guarantee customers open access to the Internet.

The potentially precedent-setting move stems from a complaint against Comcast Corp. that the company had blocked Internet traffic among users of a certain type of "file sharing" software that allows them to exchange large amounts of data.

"The commission has adopted a set of principles that protects consumers access to the Internet," FCC Chairman Kevin Martin told The Associated Press late Thursday. "We found that Comcast's actions in this instance violated our principles."

Martin said Comcast has "arbitrarily" blocked Internet access, regardless of the level of traffic, and failed to disclose to consumers that it was doing so.

Company spokeswoman Sena Fitzmaurice on Thursday denied that Comcast blocks Internet content or services and that the "carefully limited measures that Comcast takes to manage traffic on its broadband network are a reasonable part" of the company's strategy to ensure all customers receive quality service.

Martin will circulate an order recommending enforcement action against the company on Friday among his fellow commissioners, who will vote on the measure at an open meeting on Aug. 1.

The action was in response to a complaint filed by Free Press and Public Knowledge, nonprofit groups that advocate for "network neutrality," the idea that all Internet content should be treated equally.

Martin's order would require Comcast to stop its practice of blocking; provide details to the commission on the extent and manner in which the practice has been used; and to disclose to consumers details on future plans for managing its network going forward.

The FCC approved a policy statement in September 2005 that outlined a set of principles meant to ensure that broadband networks are "widely deployed, open, affordable and accessible to all consumers."

The principles, however, are "subject to reasonable network management."

Comcast argues that the agency's policy statement is not enforceable and that the commission has "never before provided any guidance on what it means by 'reasonable network management.'"

If a majority of commissioners side with Martin, it will be the first test of the agency's network neutrality principles. Members of both the House and Senate have sponsored network neutrality bills, but they have never come close to becoming law.

Large Internet service providers have fought against such regulation, arguing that it is a solution in search of a problem and that companies that spend billions on their networks must be free to manage traffic.

Ben Scott, federal policy chief for Free Press said Thursday night the FCC's action may have consequences for other Internet providers going forward.

"This is going to be a bellwether," he said.

Martin, a Republican, will likely get support from the two Democrats on the commission, who are both proponents of the network neutrality concept. Those three votes would be enough for a majority on the five-member commission.