A man has been sentenced to jail for using spyware to gain unauthorised access to US government computers.

Kenneth Kwak, a 34-year-old system auditor who had been working on the computer security of the US Department of Education, admitted placing spyware software on his supervisor's PC.

This software enabled him to access emails and other information. Kwak, of Chantilly, Virginia, then shared the information he gathered with others in his office at the government department.

US District Judge Royce Lamberth sentenced Kwak to five months in prison, followed by five months of electronically monitored home confinement. He has also been ordered to pay the US government $40,000 (£21,270), and will be on probation for three years.

"The US Government has adopted a zero tolerance policy regarding intrusions into its computer systems," said Graham Cluley, senior technology consultant for Sophos . "A clear message is being sent out to its staff that hacks like this are not just unacceptable but also criminal.

"Kwak should be thankful that no evidence was found that his hack was financially motivated, as that surely saved him from a stiffer jail term," continued Cluley.

Cluley said this was a timely reminder that organisations should put measures in place to reduce the risks.

These involved not only external attacks by malware and internet hackers, but also of potential problems with disgruntled staff or those with a financial motive in mind.