Three peer-to-peer online video distribution startups on Thursday blasted a government filing made by Comcast in which the cable operator said it does not discriminate against a particular class of content providers.

Representatives from BitTorrent, Vuze, and Miro charged that Comcast is acting in an anti-competitive fashion by deliberately blocking or interfering with P2P video traffic between their firms and customers.

In response to a filing made to the U.S. Federal Communications Commission by a group making the same charge, Comcast, late Tuesday, filed a rebuttal saying that it manages traffic on its network so that its users don't experience service degradation.

“The carefully limited measures that Comcast takes to manage traffic on its broadband network -- including its very limited management of certain P2P protocols -- are a reasonable part of Comcast’s strategy to ensure a high-quality, reliable Internet experience for all Comcast High-Speed Internet customers," Comcast said in its filing. 

In a news conference on Thursday hosted by Free Press and the SavetheInternet.com Coalition, Jay Monahan, general counsel of Vuze, a Palo Alto, California based firm that distributes HD content said his company can not build a business on that kind of uncertain delivery.

"Our users want their content fast and anything that slows it down can be as damaging as outright blocking," he said. "Anything that slows down the delivery of the content can cause users to abandon the service."

He charged that Comcast and other service providers are being anti-competitive because they have their own libraries of video content.

"Comcast not only owns a horse in the race, they own the whole racetrack," Mr. Monahan said.

But a Comcast spokeswoman said that management of traffic on its network is necessary because bandwidth is a finite resource and even a small number of users employing P2P protocols can overwhelm the network during times of high usage.

"As little as fifteen people doing P2P uploads on a node can degrade the quality for all the rest of the customers," said Sena Fitzmaurice, spokeswoman for Comcast. "Only in times of congestion we manage P2P uploads, not downloads, because very often during uploads people are not even at their computer."

The debate over traffic management is simply a subset of a larger debate about network neutrality that has raged in fits and starts in the U.S. for almost two years.

But the debate has been revived, as a new network neutrality bill sponsored by Reps. Ed Markey (D-Massachusetts) and Chip Pickering (R-Mississippi) was introduced on Tuesday.