"We are pleased to see that Internet Explorer 7's Phishing Filter finished at the top of 3Sharp's list as most accurate anti-phishing technology," Tony Chor, a group program manager for Internet Explorer at Microsoft, wrote on a corporate blog.

In the study, 3Sharp tested the products' ability to catch 100 known phishing Web sites over a six-week period earlier this year, Microsoft said. 3Sharp did not use the same sources used by Microsoft for the IE 7 protection to obtain the phishing links, it said.

"They worked hard to build large enough sample sizes of actual phishing sites to draw meaningful conclusions," Chor wrote.

IE caught nearly 9 out of 10 phishing sites and it did not show warning or block errors on the 500 legitimate Web sites tested, according to Chor.