Sir Tim Berners-Lee—inventor of the world wide web—is the latest voice to raise concerns about a meeting of communication tech regulators in Dubai.
He spoke of concerns that some attendees would push for a UN agency to "run the internet" rather than leaving it to groups already "doing a good job".
Internet pioneer Vint Cerf has also highlighted the issue on Google's site.
But the UN agency itself is playing down suggestions of a power-grab.
Dr Hamadoun Toure, secretary-general of the UN's International Telecommunications Union (ITU), said ahead of the event: "There is no need for the ITU to take over the internet governance."