As online shoppers gear up for a season of intensive spending in the run up to Christmas, online fraudsters are also preparing for their busiest time of the year.

Online shoppers spent nearly $10bn during the holiday season last year, 24 per cent more than in 2004, indicating a significant number people at risk.

Security company PC Tools, which specialises in detecting spyware and viruses, warned that shoppers should exercise caution when going to new internet sites to make purchases.

Consumers are advised to look for labels indicating that transactions are protected, and should make purchases from trusted providers if possible. Shoppers should never provide personal information in response to an email request.

"One in 10 holiday shoppers can expect some form of spyware, adware or other internet attack as they conduct transactions on the web," said Michael Greene, vice president for product strategy at PC Tools.

"Many consumers are simply not aware that surfing the web can cause problems leading to identity theft or computer lock up."

Greene added that holiday shopping is perfect for hackers who use spyware, key-loggers and phishing techniques to cull passwords and sensitive information from users.