In a column in the Daily Telegraph newspaper, the mayor of London called upon President Obama to call off the US effort to extradite and prosecute the British hacker, accused of breaking into US military computer systems in 2001.

Mayor Boris Johnson called US efforts to prosecute self-acknowledged hacker Gary McKinnon a "legal nightmare". "To listen to the ravings of the US military, you would think that Mr. McKinnon is a threat to national security on a par with Osama bin Laden," Johnson wrote.

"According to the Americans, this mild-mannered computer programmer has done more damage to their war-fighting capabilities than all the orange-pyjama-clad suspects of Guantanamo combined."

Johnson then said it would be "brutal, mad and wrong" to send McKinnon to the US for prosecution and then asked Obama to call the US Department of Justice off the case.

McKinnon, who was an unemployed system administrator in the UK at the time of the 2001 hack, has been using a series of legal manoeuvres and appeals over the past seven years to fight extradition to the United States. McKinnon, now 43, was indicted in November 2002 in the US District Court for the Eastern District of Virginia. He has said he broke into US military computers hoping to uncover evidence of UFOs.

McKinnon has admitted to hacking the computers and described how he did it in detail at computer security conferences in London.

The US government alleges McKinnon's caused $900,000 (approx £630,000) in damages to computers in 14 states, and caused the shutdown of critical military networks shortly after the September 11, 2001 terrorist attacks. He faces a sentence of 60 years or more in the US.

Late last week, McKinnon got yet another chance to avoid extradition when The High Court in London ruled that the case can be reviewed by Keir Starmer, director of public prosecutions for England and Wales.

Johnson, a high-profile politician in the UK, contends in his column that McKinnon meant no harm to the US and was only looking through government and military files for evidence of UFOs.

"It is a comment on American bullying and British spinelessness that this farce is continuing, because Gary McKinnon is not and never has been any kind of threat to American security," he wrote.

"It is time for Barack Obama to show the new leadership the world has been crying out for. It is time for the Commander-in-Chief to tell the US military to stop being so utterly wet, dry their eyes, and invest in some passwords that are slightly more difficult to crack."

Investigators and prosecutors in the US didn't take the hack as lightly, though.

The hack, which started just a few weeks after the terrorist attacks of September 11, 2001, had investigators working around the clock to figure out who had been in and out of key military systems, according to Scott Christie, who at the time was an assistant US attorney in New Jersey and was the first prosecutor brought into the case.

Christie said in a previous interview that because of the seriousness of the attack and the possibility that it could have been linked to a terrorist organisation, the government was forced threw a lot of resources at the problem - resources that could have been used in the 9/11 investigation.