The US, UK and Canada say they will not sign an international communications treaty under discussion in Dubai.
The three countries had objected to calls for all states to have equal rights to the governance of the internet.
Russia, China and Saudi Arabia were among those pushing for the change.
It marks a setback for the UN's International Telecommunication Union which had said it was sure it could deliver consensus.
"It's with a heavy heart and a sense of missed opportunities that the US must communicate that it's not able to sign the agreement in the current form," said the US ambassador to the World Conference on International Telecommunications (Wcit).
"The internet has given the world unimaginable economic and social benefit during these past 24 years."
Some other delegates have said they would now need to consult with their governments to decide how to proceed.