NatWest has topped the list of most popular company names used by fraudsters when targeting the personal finance industry.

Anti-spam firm ClearMyMail reviewed all spam and fraudulent emails blocked in December 2007 to identify the financial services companies most preferred by hackers.

ClearMyMail said that every one of its customers was sent an average of 18 fake NatWest phishing emails, 12 Citibank emails, five HSBC emails, three Abbey emails and two Lloyds TSB emails during December.

"Without any email protection UK online banking customers are at severe risk of being tricked into giving away their account details to criminal gangs," said Dan Field, managing director of ClearMyMail.

"The phishing emails are very well constructed and often look exactly like a legitimate message from the bank."

To help prevent users from falling victim to these attacks, the company has written a free guide on how to spot phishing emails.

"People without home spam and anti-fraud email protection have to remain very vigilant," said Field.

"It has almost got to the stage where cyber-crooks are building up email databases containing contact information that is profiled to fit a certain bank's or building society's typical customer in order to improve the success rate of their attacks."

ClearMyMail Top 10 list of targeted brands in December 2007:

1. Natwest (41 per cent)
2. Citibank (27 per cent)
3. HSBC (11 per cent)
4. Abbey (6 per cent)
5. Lloyds TSB (4 per cent)
6. PayPal (2 per cent)
7. Royal Bank of Scotland (1 per cent)
8. Nationwide (1 per cent)
9. Halifax (0.8 per cent)
10. MBNA (0.5 per cent)