Users of the Firefox web browser have been flocking to Netcraft's website to download the security company's new antiphishing toolbar.

The free toolbar, released Tuesday, was downloaded more than 60,000 times within hours of its release, according to Netcraft Internet Services Developer Paul Mutton. By comparison, the company's antiphishing toolbar for Microsoft's Internet Explorer (IE) browser has been downloaded around 100,000 times since its release earlier this year, he says.

"This seems to indicate that the Firefox community is more interested in security," Mutton says.

An increase in phishing attacks has been grabbing the attention of internet merchants, end users and security providers alike. Phishing is a type of online fraud in which criminals send emails that entice users into visiting websites designed to look like those of a legitimate company, such as a bank or auction provider, for example. Users are asked to enter sensitive information such as a credit card number or passwords.

Netcraft's antiphishing toolbar seeks to thwart these kinds of threats by blocking access to reported phishing sites. Once the first recipients of a phishing email report the URL of a fake site, the site is blocked for toolbar users.

Netcraft checks each reported site to verify that it is phony, in order to avoid blocking legitimate sites, Mutton says.

The toolbar also displays the hosting location and a risk rating for each site visited. While the product is free for internet users, Netcraft licenses a version to organisations such as banks to put their own brand on.

Netcraft has no current plans to offer versions of the toolbar for other browsers.

"There's no other browser as popular as Firefox right now," Mutton says. The open source browser, offered by the Mozilla Organisation, has nowhere near the market share of IE, but has been steadily gaining users.

Internet companies have taken note of its rising popularity. Yahoo began offering a toolbar for Firefox earlier this year, and Google has snapped up one of its key developers. But with success has come a downside: Security researchers are reporting an increase in threats aimed at the alternative browser.

When it comes to phishing, at least, Netcraft hopes to have an answer. "People are showing a lot of interest in the Firefox toolbar," Mutton says.