US regulators have voted for a controversial proposal that would allow service providers to sell internet "fast lanes" to certain websites while leaving open the possibility of tougher regulations to protect online access.
Amid demonstrations outside its meeting and after weeks of lobbying from various groups, the Federal Communications Commission voted 3-2 in favour of the new rules, which must still go through a public comment period before being finalised.
The plan, which aims to replace rules struck down by a US federal court, seeks to keep some principles of "net neutrality" - the notion that all online traffic should be treated equally - while allowing commercial deals authorising companies to pay for faster internet access.
The FCC said the proposed rules may allow special deals for priority access but that each would be examined for "commercial reasonableness".
At the same time, the commission said it was keeping open the possibility of regulating internet access as a public utility, which could give the FCC greater authority over access providers.
The plan was touted as a means to preserve an "open internet" but did not placate critics on either side of the issue - those who want a guarantee of equal access, and those seeking less regulation that allows deals for faster speeds.
Michael Weinberg, of the activist group Public Knowledge, said the proposal "remains insufficient to guarantee a truly open and neutral internet".
He said the proposal "would create a two-tier internet where 'commercially reasonable' discrimination is allowed on any connections that exceed an unknown 'minimum level of access' defined by the FCC".
Scott Cleland, a consultant and chairman of the business group NetCompetition representing telecom and internet firms, said the plan left open the possibility of heavy-handed regulation that "would require every business decision of consequence to be approved by the FCC".
Michael Powell, president of the US National Cable and Telecommunications Association which includes big internet firms such as Comcast, said "we will continue to reiterate our unwavering opposition to any proposals that attempt to reclassify broadband services under the heavy-handed regulatory yoke" of FCC rules.
Backers of so-called net neutrality say tougher rules would prevent big internet firms from slowing or degrading services like video-streaming outfit Netflix, and new emerging services.
Debate on the issue became muddled earlier this year when Netflix signed a deal with Comcast to pay for improved network access, even though the company has long opposed the notion of "tolls" on the internet.
The plan seems likely to generate more protests such as the one outside the FCC, which drew several hundred people.
"If we start creating express lanes on the internet, they're only going to be reserved for a small handful of big companies and those that can afford to pay them huge, huge rates," said Craig Aaron, president of the activist group Free Press.