Google has introduced a new service that allows Gmail users to access their email account via a mobile phone.

Called Gmail Mobile and accessed via http://m.gmail.com, Google says that the page will automatically optimise its interface for whatever phone you are using, adjusting it depending on the size of your mobile phone screen.

The service also allows users to open attachments such as photos, Microsoft Word documents and PDF files.

The service also lets you reply by call to people whose phone numbers are in your Gmail Contacts list.

The move is seen as the latest in a long line of moves by Google, Yahoo and MSN, who are all competing for users in the free email sector.

Yahoo already offers a mobile version of its email service, and upped the storage capacity of its accounts to 1GB.

The company has also launched a new feature that allows Gmail users to arrange your contacts into groups, so you can easily send messages to a number of people at once as well as giving people the out of office option to tell people you aren't able to check your email.