Self-confessed NASA hacker Gary McKinnon is appealing to outgoing president George W Bush to halt McKinnon's extradition from Britain to the United States.

McKinnon's legal team has requested that UK foreign secretary David Miliband press for a pardon from Bush, McKinnon's solicitor Karen Todner announced at a press conference on Thursday. "We have asked David Miliband to seek consent to ask for a pardon," said Todner.

The solicitor added that McKinnon's defense team had already applied for a pardon from Bush, but had been rejected on the grounds that McKinnon was not a US citizen.

McKinnon is also hopeful that president-elect Barack Obama will drop the extradition after his inauguration on Tuesday 20 January. "A lot of us have looked at Obama as a new hope," McKinnon told the press conference in London.

The U.S. government has accused McKinnon of "the biggest military hack of all time". U.S. prosecutors claim that between 2001 and 2002, McKinnon accessed over 73,000 army, navy, air force and NASA computers, causing $700,000 (430,000) damage by deleting files.

McKinnon has admitted hacking US military systems, but denies causing damage. He claims he was initially searching for data about UFOs, and also found evidence of anti-gravity projects.

The appeal to Bush coincides with an attempt by McKinnon to halt his extradition by pleading guilty to UK computer offenses. Todner sent a confession signed by McKinnon to director of public prosecutions Keir Starmer on December 23. In the confession letter McKinnon gave assurances that he would plead guilty to offenses under section 2 of the Computer Misuse Act (CMA) in an attempt to secure a UK jail term. Section 2 of the CMA deals with "unauthorized access with intent to commit or facilitate commission of further offenses."

McKinnon told ZDNet UK on Thursday he was hopeful Starmer would agree to prosecute in the UK.

"[The confession] makes [Starmer's] job easier," said McKinnon. "It gives him a home run."

Starmer will reach a decision within four weeks, Todner told ZDNet UK on Thursday.

In addition, on Tuesday January 20 the High Court will hear oral evidence from McKinnon's legal team. McKinnon's defense contend that McKinnon's diagnosis of Asperger's Syndrome in the summer was not taken into account by the home secretary Jacqui Smith when she rejected McKinnon's second appeal against extradition in October.