Comcast has explained its controversial practice of limiting peer-to-peer traffic in a filing with the Federal Communications Commission (FCC).

The US cable provider claimed that it had limited traffic on peer-to-peer networks in an effort to free up bandwidth for all users.

"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 experience for all Comcast high-speed internet customers," the company said in its filing.

Comcast made the filing in an effort to stave off a campaign by groups alleging that the firm violated the FCC's 2005 Internet Policy Statement, which prohibits providers from blocking specific lawful services or devices.

Researchers had accused Comcast of blocking traffic when an independent investigation first suggested that the provider was locking off BitTorrent traffic from its users.

Comcast claims that it does not indiscriminately lock down all peer-to-peer traffic, but does limit traffic that would slow broadband speeds for other users.

"Network management that is reasonable and done for the benefit of subscribers is critical to every broadband service provider's ability to offer its customers the quality and reliability subscribers demand and expect," the company said.

Net neutrality groups, however, do not accept Comcast's explanation. Marvin Ammori, general counsel at Free Press, explained in a statement that the real reason behind Comcast's move is to hamstring other services.

"Cut through all the jargon, and this much is clear: Comcast is not managing bandwidth hogs, it is undercutting competition," he said.

"Comcast is looking at a future where consumers can access millions of channels online without its permission, and does not like it."