Edmund Lawson QC, told two judges that, if extradited, Mr McKinnon would face the prospect of an unknown length of time in pre-trial detention, with no likelihood of bail.

Made threats

If found guilty, he would then face a very long prison sentence "in the region of 45 years, if not more", said Mr Lawson.

There was also the prospect that he would not be allowed to be repatriated to serve part of that sentence at home in the UK.

Mr Lawson said the US authorities had made threats during the plea bargaining attempt in 2003 which infringed his family and private life rights under Article Eight of the European Convention on Human Rights.

Mr McKinnon has never denied that he accessed the computer networks of a wide number of US military institutions between February 2001 and March 2002. He was arrested in November 2002.

He has always maintained that he was motivated by curiosity and that he only managed to get into the networks because of lax security.

The hearing continues.