The University of Tennessee college student accused of illegally accessing Alaska Governor Sarah Palin's Yahoo email account was formally charged Monday on new fraud and obstruction of justice charges.

David Kernell was arraigned Monday in US District Court for the Eastern District of Tennessee, five months after a federal grand jury first handed down charges against him.

He had been facing just one count of illegally accessing a protected computer, but prosecutors are now accusing him of three counts of computer fraud charges and one count of obstruction of justice. All four charges are felonies.

Kernell pleaded not guilty to the charges, according to court records. Neither his attorney Wade Davies, nor Gregory Weddle, the assistant US attorney working on the case, returned messages seeking comment.

During last year's presidential race, Kernell used publicly available information to reset the password for Palin's [email protected] account, and then posted information from that account to an online bulletin board at 4chan.org, prosecutors say in court filings. Kernell also posted the reset passwords to Palin's account, which was used by at least one other person to access the account.

Kernell is the son of Mike Kernell, a Democratic state representative from Memphis.

Palin's email messages were posted to the Wikileaks.org Web site on 17 September, and the hack attracted national media attention. Within days, Kernell was linked to the incident by bloggers who concluded that he was the same as the anonymous hacker named Rubico who had first posted the Palin data.

According to reports, Rubico had been hoping to find something that would "derail" Palin's vice-presidential campaign.

Worried that the US Federal Bureau of Investigation was on his trail, Kernell deleted records on his laptop computer in hopes of hiding his tracks, prosecutors say.

His trial is set to begin on 27 October.