The US Federal Communications Commission has voted to repeal landmark 2015 rules aimed at ensuring a free and open internet, setting up a court fight over a move that could recast the digital landscape.

The approval of FCC Chairman Ajit Pai's proposal marks a victory for internet service providers and hands them power over what content consumers can access.

Democrats, Hollywood and companies such as Google parent Alphabet Inc and Facebook Inc had urged Mr Pai, a Republican appointed by US President Donald Trump, to keep the Obama-era rules barring service providers from blocking, slowing access to or charging more for certain content.

Consumer advocates and trade groups representing content providers have planned a legal challenge aimed at preserving those rules.

The meeting was evacuated before the vote for about ten minutes due to an unspecified security threat, and resumed after sniffer dogs checked the room.

New York Attorney General Eric Schneiderman, a Democrat, said in a statement he will lead a multi-state lawsuit to challenge the reversal.

He called the vote "a blow to New York consumers, and to everyone who cares about a free and open internet".

FCC Commissioner Mignon Clyburn, a Democrat, said in the run-up to the vote that Republicans were handing the keys to the internet to a handful of multi-billion dollar corporations.

Shares of Alphabet, Apple Inc and Microsoft Corp moved lower after the vote.

Mr Pai has argued that the 2015 rules were heavy handed and stifled competition and innovation among service providers.

"The internet wasn’t broken in 2015. We weren’t living in a digital dystopia. To the contrary, the internet is perhaps the one thing in American society we can all agree has been a stunning success," he said.

The FCC voted three to two to repeal the rules.

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Consumers are unlikely to see immediate changes resulting from the rule change, but smaller startups worry the lack of restrictions could drive up costs or lead to their content being blocked.

Internet service providers say they will not block or throttle legal content but that they may engage in paid prioritisation.

They say consumers will see no change and argue that the largely unregulated internet functioned well in the two decades before the 2015 order.