WASHINGTON (Reuters) - The top U.S. communications regulator plans to unveil proposals Monday for ensuring Web traffic is not slowed or blocked based on its content, sources familiar with the contents of the speech said on Friday.

Customers look over Apple products at the company's retail store in San Francisco, California April 22, 2009. REUTERS/Robert Galbraith

Federal Communications Commission Chairman Julius Genachowski will announce plans to ask his fellow commissioners to adopt as a rule net neutrality and four existing principles on Internet access issued by the agency in 2005, one of the sources said.

Net neutrality pits open Internet companies like Google Inc against broadband service providers like AT&T Inc, Verizon Communications Inc and Comcast Corp, which oppose new rules governing network management.

Advocates of net neutrality say Internet service providers must be barred from blocking or slowing traffic based on its content.

But service providers say the increasing volume of bandwidth-hogging services, like video sharing, requires active management of their networks and some argue that net neutrality could stifle innovation.

“He is going to announce rulemaking,” said one source familiar with the speech due to be delivered at the Brookings Institution, a public policy think tank.

The rule proposal will also try to seek greater clarity into what constitutes “reasonable” network management by Internet providers.

The FCC could formally propose the rule aimed at both wireless and landline Internet platforms at an open meeting in October.

Because of the implications for applications such as Internet phone calling services, like those provided by eBay Inc’s Skype and Google, agency staff are expected to propose setting a lengthy public comment period before any final action.

The Monday speech coincides with a deadline for the FCC to file a court brief in a case against Comcast, which is challenging whether the agency has the authority to regulate actions involving the Internet.

The FCC is expected to defend its position by arguing that the agency has broad authority under the 1996 Telecommunications Act.

Public interest groups praised Genachowski for moving forward with a rule that would protect speech and commerce, predicting the policy move would be a big win for consumers.

“It will be a big win for consumers if the FCC delivers strong net neutrality rules that apply across all technologies,” Ben Scott, policy director at Free Press, said in a statement.