The Office of Fair Trading (OFT) is warning companies to beware of the pressure tactics used to sell internet domain names.

Companies are regularly cold-called by domain name sellers claiming to have discovered that a rival is interested in buying a domain name similar to theirs.

The sellers often suggest that the 'buyer' is a rival company or disgruntled ex-employee, and that the company has only a short time in which to buy the domain.

But in many cases there is little evidence that such mystery buyers actually exist.

The OFT said it would consider invoking the Misleading Advertising Act if it could prove a domain name seller was flouting the law.

It has issued warnings to some companies about their selling practices and will continue to monitor the situation.

An OFT spokeswoman told vnunet.com: "We haven't got enough proof that there really isn't a third-party buyer. We are asking these resellers to keep records of third-party interest. If we have complaints we can then check.

"If there are no records we could take further action under the Misleading Advertising Act, such as taking the reseller to court."

If companies have any doubts about the reliability of a domain name offer, they should contact their Internet Service Provider, their usual domain name registration agent or their local trading standards service, which can advise on a course of action.