The next version of the Firefox has been delayed thanks to security problems with the existing browser.

It will now be released in the late summer and promises new features including an automatic update service - particularly useful as it is the slew of recent security patches for Firefox that has set the latest version back.

Chris Hofmann, lead engineer at The Mozilla Foundation, which oversees the Firefox project, denied the browser had been delayed, claiming: "There really hasn't been any official date." The target time frame for a new release has always been mid to late summer, he said.

The next release of the Firefox 1.0 browser has generally been referred to until now as version 1.1, but that is now being changed to Version 1.5. The reason, Hofmann said, is that it will be easier for developers to test interim versions of the software using a wider gap in the version numbers. However, Tristan Nitot, president of Mozilla Europe, has gone on record as saying that the new name reflects the fact that many more features than were originally planned for 1.1 will now be present in the new version. The release may have been set back, but developers are continuing to work on extra features.

So far, developers are making good progress in adding features to the upcoming version of Firefox, including development features that can be used to encourage additional Web applications for the browser, Hofmann said.

First and second alpha releases of the application were released last month, and a beta version is expected soon. But no specific date has been offered for when the beta will be available.

Earlier this week, The Mozilla Foundation announced that international versions of Firefox and the Thunderbird e-mail client would be delayed so that several recent security fixes could be included. The delay arose from a number of software glitches that were introduced in last week's release of English-language versions of Firefox and Thunderbird.

The open-source browser was released in November last year for free download and has grown as a popular alternative to Internet Explorer. It has been downloaded 50 million times, according to The Mozilla Foundation.