Google is set to release a new version of Gmail today.

Google will today unveil a new version of Gmail and other consumer internet services for office use, marking the start of a new battle with corporate software giants such as Microsoft and IBM.

The services being launched will take Google into the nascent market known as "software as a service", where companies rely on services delivered over the internet instead of buying software to run on their own machines.

"I think it's an incredible opportunity - software as a service is really taking off because you only buy what you want," said Dave Girouard, general manager of Google's enterprise group. "Our view is that over time a lot of our applications for individuals really are enterprise applications."

Corporate Gmail will carry advertising like the consumer version but businesses will also be able to brand it themselves. Google says that by the end of this year it plans to offer a separate version that companies can pay to use.

However, analysts say that despite the rapid growth of newer companies such as Salesforce.com, which has proved the appeal of software as a service, it is still an emerging market and one in which most big companies are proceeding cautiously.