WASHINGTON – US government regulators agreed on Thursday to begin drafting rules that would require Internet service providers (ISPs) to treat all Web traffic equally.

Federal Communications Commission (FCC) chairman Julius Genachowski and two other Democrats voted in favor of crafting rules on "network neutrality" -- the principle that ISPs provide the same speed and level of service to all Web users, regardless of size.

The new rules would prevent ISPs, for example, from blocking or slowing bandwidth-hogging Web traffic such as streaming video or other applications that put a strain on their networks or from charging different rates to users.

During his White House campaign, President Barack Obama came out strongly in favor of net neutrality, which is backed by companies such as Google, Amazon, Yahoo!, eBay and consumer advocacy groups, but opposed by telecommunications, wireless and cable companies.

Two Republicans on the FCC also voted on Thursday to go ahead with the rule-making process, which will be open for public comment until January 14, but voiced misgivings about the plan.

A leading Republican, Senator John McCain, the party's former presidential candidate, introduced legislation meanwhile seeking to block the FCC move, calling it "onerous federal regulation."

McCain said the "Internet Freedom Act of 2009" will keep the Internet "free from government control and regulation."

FCC chairman Genachowski argued, however, that "reasonable and enforceable rules of the road" were needed "to preserve a free and open Internet."

"The Internet's openness has allowed entrepreneurs and innovators, small and large, to create countless applications and services without having to seek permission from anyone," he said.

But, the FCC chairman said, there have been "some significant situations where broadband providers have degraded the data streams of popular lawful services and blocked consumer access to lawful applications."

The draft proposed rules would allow broadband Internet providers to conduct "reasonable network management" and block spam, unlawful content such as child pornography and files that infringe copyright.

But they would not be allowed to discriminate against lawful content.

Amazon, eBay, Facebook, Google, Twitter and other leading Web and technology companies expressed support earlier this week for the FCC's efforts.

"America's leadership in the technology space has been due, in large part, to the open Internet," they said in an open letter.

Kyle McSlarrow, president and chief executive of the National Cable and Telecommunications Association, said his industry group planned to "fully participate" in the rule-making process.

"We welcome the opportunity to make our case that investment, innovation and consumer welfare are all enhanced by continued government restraint," he said.

"To be clear, we regard this as a debate about means, not ends; we support a free and open Internet," McSlarrow added. "However, we continue to believe the broadband marketplace is an unparalleled American success story and already offers consumers an open Internet experience."