The 20 year-old son of Democratic state legislator Mike Kernell has been indicted for hacking into the email account of Republican vice-presidential candidate Sarah Palin.

David Kernell was arrested after an FBI investigation into the incident in which the password of Palin's Yahoo account was changed and details of her emails posted online by an individual known as 'rubico'.

If found guilty, Kernell could face five years in prison and a fine of $250,000 (£145,000).

"Cyber-crime is the FBI's top criminal investigative priority," said Richard Lambert, special agent in charge, FBI Knoxville Field Division.

"We would like to thank all of the internet service providers and others who partnered with us to bring this matter to a quick and successful resolution."

Kernell was released from court without bail but is banned from owning a computer and can only use the internet to check email and complete his class work.

As hacking attacks go, this one seems to have been rather amateurish. Kernell posted screenshots of the email that included information about his ISP, and his postings on a message board were quickly tracked back to his email address.

However, the case highlighted the improper use of a webmail account for official government business. Under oversight rules all state business should be conducted over government email systems so that all records can be checked.