Gullible consumers have been warned to be on their guard against Internet sites offering miracle cures and wonder drugs for sale.

A simultaneous sweep of the World Wide Web by enforcement agencies in 20 countries uncovered sites advertising products such as a Japanese slimming soap which can "wash away fat in seconds".

Other unscrupulous firms promised a two-week cure for cancer using an American herbal medicine, a toffee-like hair restorer which "actually works" and books listing remedies for all cancers, HIV and Aids.

In all, 60 agencies worldwide scoured the Web for misleading medical claims.

The Australian-led operation was a repeat of one undertaken last year which targeted bogus get-rich-quick schemes.

Mr John Bridgeman, Director General of Fair Trading in Britain, warned people to use their common sense.

"If something sounds too good to be true it probably is," he said.

He said that although consumer protection legislation varied from country to country, dishonest Internet site operators could find themselves liable under laws other than those of their home nation.

"This exercise has been an example of international co-operation in practice, aimed at maintaining an enforcement presence on the Net, and educating website operators about existing legislation," he added.

The Australian Competition and Consumer Commission is collating results of the sweep.