Internet users are being warned to be on the look out for letters that appear to be invoices for domain names they have not purchased.
Nominet concerned about confusion created
The UK domain name registry, Nominet, is asking people who own co.uk web addresses to let them know if they have received one of these letters.
The unsolicited mailings have been sent by a company called UK Internet Registry, which seems to be based in the Seychelles.
The note says that the .com version of a co.uk name is unregistered, offering to sell it for a total of £175.
In its statement, Nominet said it was "concerned about the confusion that had been created by the sales tactics of UK Internet Registry".
The letters offer a .com address for £69 and a further £106 for web and e-mail forwarding.
Nominet has warned people not to be "bounced into registering a domain name by the pressure selling tactics of an unknown third party".
Instead, the owners of web addresses should get in touch with their usual domain name provider.
The UK registrar was keen to distance itself from UK Internet Registry, saying it did not proactively sell .uk domain names and was not involved in the registration of .com addresses.
It is now investigating whether UK Internet Registry has been able to get a list of the more than three million registered UK web addresses, and, if so, where it came from.
Nominet is asking anyone who might have received a letter to send it a copy.
A copy of the letter has been put up on the web by the domain name company Internetters.
Details about the company behind the mailing are sketchy. Its website says the UK Internet Registry is based in London but it did not come up on the database of UK businesses at Companies House.
The terms and conditions on the site say the agreement is governed by the laws of the Seychelles, suggesting this is where the company is registered.
The domain name ukinternetregistry.com was only registered on the 6 February and the co.uk version a few days later.
Calls to the contact number on its website have gone unanswered.