About 57,000 seemingly legitimate websites booby-trapped by hackers spring up on the Internet each week, computer security researchers at PandaLabs revealed on Thursday.

The online traps are often made to look like versions of legitimate bank, auction, or shopping websites, according to the team at Spain-based Panda Security.

"The problem is that when you visit a website through email or search engines, it can be difficult for users to know whether it is genuine or not," said PandaLabs technical director Luis Corrons.

"Although search engines are making an effort to mitigate the situation by changing indexing algorithms, they have so far been unable to offset the avalanche of new websites being created by hackers every day."

Cyber crooks try to pass their rigged websites off as legitimate, putting links in emails or posts at social networks and getting them listed in query results at search engines.

Bogus websites are typically designed to slip viruses onto visitors's computers and trick people into typing in valuable information such as account names or passwords.

Online auction house eBay and money transfer service Western Union were top choices for hackers, each being subjects of fake websites in more than 20 percent of the cases found by a PandaLabs study that spanned three months.

The PandaLabs list of the top 10 companies impersonated included Visa, Amazon.com, PayPal, HSBC, and the US Internal Revenue Service.

Nearly two-thirds of the trick websites had to do with banks, according to PandaLabs.

"Given the proliferation of this technique, we advise consumers to visit banking sites or online stores by typing in the address in the browser directly rather than using search engines or links in an email," Corrons said.