iPhone owner and US Democratic presidential candidate Barack Obama has launched an iPhone application.

The free software is designed to rustle up extra support in the last month of campaigning before America votes.

Features include a "Call Friends" function where contacts are prioritised by "key battleground states", and call stats so users can compare their call totals to others'.

There's also updates with latest news and announcements, national and local campaign news and links to media, such as photos and video, about the campaign.

In addition, the app covers "issues" with the option for users to "get clear facts about Barack Obama and Joe Biden's plan for essential issues facing Americans".

Obama has used Facebook and YouTube in his campaign previously and is described as a "fan of technology".