Long-awaited U.S. rules addressing the hot-button issue of balancing consumer and content providers' interests against those of Internet service providers will take effect on November 20.

The regulations covering so-called Net neutrality, published in the Federal Register on Friday, are sure to trigger legal and congressional challenges. They were adopted by the U.S. Federal Communications Commission late last year after a lengthy debate.

Criticized by opponents as a legally shaky government intrusion into regulating the Internet, the new rules forbid broadband providers from blocking legal content but leave flexibility for providers to manage their networks.

Verizon Communications Inc has been a vociferous opponent, and renewed its pledge to take the FCC to court as soon as the rules are published.

We have said all along that once we see the publication ... we intend to file another notice of appeal, Verizon spokesman Ed McFadden said.

For the past 10 years, the possibility of regulations to mandate the neutrality of the Internet -- in terms of restrictions on content, sites, platforms and types of equipment that may be attached -- has been the subject of fierce debate.

The fight pits content providers who seek protection against the blocking or degrading of their services against Internet service providers that want to control the pipeline.

The rules, adopted last December in a 3-2 vote, give the FCC power to ensure consumer access to huge movie files and other content while allowing ISPs to manage their networks to prevent congestion.

But public interest groups criticized the rules, saying they bent heavily to the will of big industry players including AT&T Inc and Comcast Corp.

Matt Wood, policy director of public interest group Free Press, said loopholes will still allow broadband providers to divide the Internet into fast and slow lanes and that the rules fail to protect mobile broadband users.

Even in their watered-down form, the rules might do some good -- but that would require a vigilant FCC to carefully monitor and address complaints, Wood said in a statement, adding that he doubted the agency would do enough to protect consumers.

The U.S. Court of Appeals for the District of Columbia Circuit in April threw out earlier challenges to the FCC's open Internet order by Verizon and MetroPCS Communications Inc, dismissing their lawsuits as premature.

That same court ruled last year that the FCC lacked the authority to stop Comcast from blocking bandwidth-hogging applications on its broadband network, a decision leading to the FCC's latest rules.

The FCC could not immediately be reached for comment.

(Reporting by Jasmin Melvin in Washington, editing by Matthew Lewis)

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