The Anti-Phishing Working Group (APWG), which studies the internet scams, reported that nearly 40 new attacks were reported every day in May.

This represents a 700% rise in the number of attacks in January this year.

Most commonly, the phishers use spoofed emails to trick recipients into handing over bank account or other financial details. Spoofs claiming to come from US banks rose 170% in May month on month.

But while the threat is growing, most of the fraudsters use relatively unsophisticated methods to trick recipients.

APWG reports that 95% of bogus emails use forged 'from' addresses to hide the sender's identity - so called domain spoofing.

'Once ISPs start to verify the source of messages, a lot of bad things in email, including phishing, will be greatly reduced,' said Dave Jevans, chairman, APWG.

Microsoft last week revealed plans to combat the problem of domain spoofing by introducing methods of checking the sender address with the IP address of the email, which is much harder to forge.