Mr McKinnon has been fighting extradition since 2002

Gary McKinnon, who is accused of breaking into US government computer networks, has been fighting extradition since his arrest in November 2002.

His family says he has 14 days to appeal against the extradition.

Mr McKinnon told the BBC he was "very worried and feeling very let down by my own government".

In May, a district judge sitting at Bow Street Magistrates' Court in London recommended Mr McKinnon be extradited - but the final decision rested with the home secretary.

'Order signed'

A Home Office spokesman said: "On 4 July the secretary of state signed an order for Mr McKinnon's extradition to the United States for charges connected with computer hacking.

"Mr McKinnon had exercised his right to submit representations against return but the secretary of state did not consider the issues raised availed Mr McKinnon.

"Mr McKinnon now has the opportunity, within 14 days, to appeal against the decisions of the district judge/secretary of state."

Mr McKinnon was first arrested in 2002 by the UK's National Hi-Tech Crime Unit for hacking into a series of computer networks used by the US army, navy, air force, and Department of Defense.

The US, in its case for extradition, said Mr McKinnon caused more than $700,000 (£375,235) of damage while exploring the computer networks at various US military institutions.

It said one attack at the Earle Naval Weapons Station took place soon after 11 September 2001 and made it impossible to use critical systems.

The US Department of Justice said it took a month to get systems working in the aftermath of this attack.

Mr McKinnon, who was born in Glasgow, has admitted that he spent almost two years exploring these networks but has said he was motivated by a search for what he called "suppressed technology".

His lawyers had argued he could be sent to Guantanamo Bay as a terrorist suspect.