A US and Canadian proposal to protect the internet from new international regulation has failed to win prompt backing from other countries, setting up potentially tough negotiations to rewrite a telecom treaty.

The idea, also supported by Europe, would limit the International Telecommunication Union's (ITU) rules to only telecom operators and not internet-based companies such as Google and Facebook.

That could reduce the prospective impact of efforts by other countries including Russia and some in the Middle East and Africa to obtain more powers to govern the internet through the ITU, an arm of the United Nations.

Those efforts, slated for discussion next week, could make Net anonymity - or the ability to remain anonymous online - more difficult to maintain and could bolster censorship, critics say.

"We want to make sure (the rewritten ITU treaty) stays focused squarely on the telecom sector," said US Ambassador Terry Kramer. "We thought we should deal with that up-front."

Kramer had been hoping that a committee comprising representatives from six regional bodies would give quick approval to the American request on Tuesday. But that failed to happen.

An ITU spokesman said late on Tuesday that the talks were continuing and that the issue would only return to the main policy-making body on Friday.

About 150 nations are gathered in Dubai to renegotiate the ITU rules, which were last updated in 1988, before the Internet and mobile phones transformed communications.

The 12-day ITU conference, which began on Monday, largely pits developing countries and regimes that want more control over internet content against US policymakers and online companies that prefer the status quo.

The internet has no central regulatory body, but various groups provide some oversight, such as ICANN, a US-based nonprofit organisation that coordinates domain names and numeric Internet protocol addresses.

To date, US companies have led innovation on the internet as well as the development and use of destructive software in military operations that take advantage of anonymous internet routing and security flaws.

Some of the proposals now being contested by the American and Canadian delegations are aimed at increasing security and reducing the effectiveness of such attacks, although the West and several rights groups argue that is a pretext for greater repression.

ITU Secretary-General Hamadoun Touré told Reuters last week that any major changes to the 1988 treaty would be adopted only with "consensus" approaching unanimity, but leaked documents show that managers at the 147-year-old body view a bad split as a strong possibility.

If that happens, debates over ratification could erupt in the United States, Europe and elsewhere.

(Reporting by Matt Smith in Dubai and Joseph Menn in San Francisco; editing by Matthew Lewis)