Pornographers say the domain would force them into a "ghetto"

The proposal for the .xxx domain was rejected in May 2006 by the overseer of the net's addressing system over fears about how it would be run.

But the proposal has won approval following promises by the domain's backer to actively police any site that signs up to use the .xxx suffix.

The plan has come under fire from pornographers and politicians.

History lesson

The idea of creating a net domain for pornography was first floated in 2001 and attempts to set up the system have had a troubled history.

The proposal was given approval in June 2005 by the Internet Corporation for Assigned Names and Numbers (Icann) which oversees the net's addressing system.

Final approval was scheduled to take place in December 2005 but this was delayed until May 2006 when the proposal was abruptly dropped.

At the time Icann boss Paul Twomey said the decision was not "politically motivated" and now documents posted on the Icann site show that the decision was taken over worries about how sites signing up to use .xxx would be policed.

As a result, ICM Registry - the backer of the .xxx scheme - has given pledges that it will ensure sites signing up do not hit users with spam or spyware. Sites will also have to use a tagging system that accurately labels their content.

ICM must also put in place systems that stop children seeing the sites and ensure no .xxx sites are used to promote child pornography or any "practices that appeal to paedophiles or suggest the presence of child pornography on the site".

Icann has now invited the public to comment on the revised .xxx agreement. Those interested have until 5 February to comment.

In the past, plans for the .xxx domain have come under fire from conservative groups, politicians and even pornographers. Some operators of adult sites fear that adopting the .xxx domain would make it easier for such sites to be blocked en masse.

Critics have also noted that use of the .xxx domain is entirely voluntary and some suspect that few sites would sign up to use the suffix.

If final approval is won it is not yet clear when the domain will start operating.