Internet monitoring company Websense has issued a warning that Chinese scammers are using search engine optimisation (SEO) techniques to subvert company details.

The scammers first send out large amounts of spam containing fake telephone numbers against the names of legitimate organisations.

This is then followed up by a second wave of spam, usually traditional lottery scams, in which users are conned into paying transfer and administration fees before they can receive a 'prize'.

"Most of these numbers belong to the Hainan province in China," said Websense.

"Many high profile names like Sina, Taobao, QQ, Tencent etc, from portal sites to shopping sites, have been used as part of the attack. Dozens of fake telephone numbers are being used to lure users into dialling."

The spam asks the recipient to call a premium customer service line, which generates extra cash for the spammers.

When users attempt to check out the companies online they find the numbers are seemingly legitimate because of the first wave of spam.

Google and Baidu are currently indexing tens of thousands of web sites containing the fraudulent telephone numbers, many of which are still active.

While the scam is primarily hitting Chinese internet users, it is likely to spread around the world and move from lottery companies to more traditional businesses.