Internet users are being warned to be on their guard for "bogus" invoices after Nominet UK received more than 100 complaints concerning an alleged scam.
The demand for £225 is for inclusion in a Web directory run by London-based Central Web Pages Register Ltd.
However, the wording on the invoice is confusing with many people believing that unless they pay up they will lose their domain names.
Nominet UK - the national registry for all domain names ending .uk - is warning people not to confuse what appears to be a domain name registration renewal invoice with what is actually the offer of an entry in a Web directory.
"This appears to be a 21st century version of the confusing fax directory invoice," said Lesley Cowley, MD of Nominet UK.
"Those contacted should treat the demand with the same caution as they would any other unsolicited invoice and, if unsure, contact their ISP for clarification."
Domain name outfit Internetters is one of those companies to have received the invoice.
In a statement Ken Sorrie, co-founder of Internetters said: "It seems as if these people have a list of .uk domain name registrants and are mailing this letter to everyone on it.
"I stress they are not an official domain name organisation and the letter should be ignored.
"What the company is actually doing is putting the people who pay-up on a list on its Web site and nothing else.
"The organisation is bogus and should be exposed," he said.
All attempts to contact Central Web Pages Register Ltd concerning the matter have so far dawn a blank. ®