A plan for a new internet "domain" for pornography has once again been shelved, dealing another blow to the US-backed addressing system that acts as the glue holding together the unified global internet.

The setback is likely to add to pressure that could eventually fragment the internet, breaking it into a collection of separate national systems, some internet experts warned.

It comes as the Internet Corporation for Assigned Names and Numbers (Icann), the organisation that administers the current addressing system under licence from the USCommerce Department, faces renewed unrest over its slow progress towards introducing domain names in languages other than English.

"If Icann and the US fail to respond to growing global concerns around internet governance, fragmentation is the likely outcome," said Michael Geist, professor of internet law at the University of Ottawa.

Pressure from conservative Christian groups in the US, which has a veto over the internet addressing system, led the organisation last year to put off introducing a new ".xxx" domain for pornography on the internet. That drew international complaints that the US exercised too much power over the internet and added to a European-backed movement to shift control of the online medium to an international group.

Supporters of the .xxx address suffix argued that it would have helped to protect children and others from accidental exposure to internet pornography, particularly if stronger filters were used to screen out explicit material from other internet domains.

Icann's board decided to drop the plan again yesterday at a meeting in New Zealand, with the US once again understood to have lodged its opposition to the idea. This time, however, the organisation was also able to point to opposition from an unspecified number of other governments. Although not having the veto power of the US, a government advisory committee set up to respond to Icann proposals said "several" of its members were against the idea.

The Australian government has already spoken out publicly against an internet porn address, while a report in New Zealand claimed that Iran was also opposed.