Andrew Harvey, 24, of Sherburn Village, Co Durham, was jailed for six months, and Jordan Bradley, 22, of Darlington, was jailed for three months, on Friday.

The men admitted a conspiracy charge in May this year for their part in creating what was called the T-K Worm.  It used internet chat channels to infect other computers which then gave the hackers control of them.

They were arrested in 2003 after a joint investigation by hi-tech crime officers in Britain and the US.  The men, who did not benefit financially from their actions, were part of a group called the Threat Krew".

Newcastle Crown Court heard how one police computer became infected with the worm and spread it to 19,000 other computers in two weeks.

Harvey, of Meldon Avenue, Sherburn Village, and Bradley, of Bates Avenue, Darlington, admitted conspiracy to cause unauthorised modification of computers with intent between 31 December 2001 and 7 February 2003.