Manwin Licensing, the chaps behind the Playboy websites, and Digital Playground are suing the internet's address regulator, Icann, as well as filing lawsuits against ICM Registry, the company behind the new top-level domain name (TLD).

The legal action is a result of the pornography companies' concerns that ICM is abusing its position and that Icann didn't seek competitive bids for the .xxx registry, and failed to conduct "proper economic studies" to support its creation.

Reports suggest that ICM is charging annual registration fees of around $60 per address which is around ten times the fee charged for other comparable top level domain names.

However, ICM has recently boasted about the success of the scheme, stating it had received over 80,000 applications for .xxx websites, with 78,938 coming from trademarked or pre-owned names. The plan, it says, is to create a "trusted brand... extolling responsible and safe behaviour".

Manwin's lawsuit states ICM "generated fake comments in support of its application" and "knowingly sold domain names to persons and entities who are known domain name speculators".

"Ending anticompetitive practices by ICM and Icann will not only protect our business, but help other companies compelled to pay a fee to keep their names unassociated with a .xxx designation," said Fabian Thylmann, managing partner of Manwin.

"The claims are baseless and without merit and will be defended vigorously," said ICM Registry president Stuart Lawley.

"They also show an apparent lack of understanding of the Icann process and the rigorous battle we went through with Icann over eight years in full public scrutiny to gain approval."

The introduction of .xxx was meant to allow the more seedy parts of the web to be placed in a set area, one that can be easily controlled and managed by search engines and users. And, it should provide the benefit of allowing search engines and parents to more effectively control access to content on those sites, as they will all have the same url ending.