Nominet UK, the national registry for .uk domain names, is warning domain name holders to beware of a company sending out false invoices.

The company, which calls itself Domain Registry Services (DRS), is sending out a 'Notice of Expiration' to owners of .com, .uk and .org names, warning that their domains are due for renewal and will cost £60 to re-register.

"The notice states that the registrant stands to lose their domain name unless the invoice is settled," said Nominet in a statement.

"The sums being demanded are many times what Nominet would charge a registration agent [seller of domain names] for registering a .uk domain name."

As well as asking for £60 for a year's registration, DRS is trying to sell registration for five years for £140 and 10 years for £270.

But .uk domain names cannot be registered for more than two years at a time. Additionally, in its 'Notice of Expiration' invoice DRS implies that it is the registry for those domains - but it is not.

A spokeswoman for Nominet said: "Nominet is concerned about how DRS is getting the information it holds about .uk domain name holders."

The national registry has already received more than 50 complaints about DRS, mainly from small businesses and internet service providers.

It has advised domain name holders to be vigilant. "These false invoices have been issued to owners of .com and .org domain names in the past, but Nominet UK has recently received information that this scam has spread to .co.uk names as well," said Nominet.

The registry said holders of .uk domains with any doubts about the validity of an invoice should contact their existing registration agent for advice.