CONTINUED:
Firefox 3 downloads blast past 5 million

Nitot said that the main problems had begun before Firefox 3 had been released.

"It's true that downloads have exceeded out wildest dreams, but there was a failure even before the sites were open," said Nitot.

A Mozilla spokesperson confirmed that there had been problems migrating the servers, but said that the issues were fixed an hour later.

"There were a few technical issues migrating the sites and servers, then we went live an hour later," said the spokesperson.

At the beginning of the release, a post by Mozilla marketing coordinator Melissa Shapiro on the Mozilla blog on Tuesday said that the interest in Firefox 3 had been "overwhelming", and that Mozilla servers were under pressure.

"The outpouring of interest and enthusiasm around Firefox 3 has been overwhelming (literally!)," wrote Shapiro at the time of the release. "Our servers are currently feeling the burn and should be back to normal shortly. Download day will officially commence once the site goes live. The 24-hour period will be clocked from that moment."

As a consequence of the release being delayed for an hour, Firefox 3's 24-hour world-record download attempt period will end on Wednesday at 7pm BST.