People using Google's Gmail service are sucking up storage space faster than the company can add it.

Google said on Friday it is speeding up the rate at which it adds storage space for its Gmail Web-based e-mail service due to the increased storage requirements for attachments such as photos.

"A few of you are using Gmail so much that you're running out of space, so to make good on our promise, today we're announcing we are speeding up our counter and giving out more free storage," wrote Rob Siemborski, a Google engineer on the Gmail blog.

On Friday, the counter on the Gmail login page stood at more than 2,935MB, or about 2.9GB, of storage, and was rising -- but the counter is an illustration rather than a hard limit.

Google started gradually increasing Gmail storage in April 2005 when the service turned one year old. Google's Gmail gained immediately popularity when it launched in 2004, offering free accounts with 1GB of storage, but this year has been surpassed by its rivals.

Microsoft upped its free storage limit for its Windows Live Hotmail service to 5GB in August, and Yahoo started offered "unlimited" storage in May.