Mozilla Corp.'s new Firefox 3 Web browser, the main rival to Microsoft Corp.'s dominant Internet Explorer, shattered the company's previous record by attracting more than 8.2 million downloads in its first 24 hours.

Firefox 3 passed its predecessor's first-day download total of 1.6 million in five hours, according to the company based in Mountain View, Calif. Mozilla released the program Tuesday.

The software, available for free, loads Web pages as much as three times quicker than Firefox 2, increases protection against malicious software attacks and makes it easier to access frequently visited sites, Mozilla said.

Firefox accounts for about 18 percent of the market for browsers, software that connects computer users to the Web, according to Net Applications, based in Aliso Viejo, Calif. Microsoft, the world's largest software maker, has 74 percent.

Microsoft began testing a new version of Internet Explorer in March.