Andrew Harvey, 23, of Sherburn Village, and Jordan Bradley, 22, of Darlington, both County Durham, admitted a conspiracy charge involving others.

The pair were arrested in February 2003 after an inquiry involving crime teams from the UK and US.

Both were granted bail until 30 September at Newcastle Crown Court.

Internet worm

Judge Beatrice Bolton warned the pair: "The reality here is that the likely sentence is a custodial one."

The pair admitted conspiracy to cause unauthorised modification of computers with intent between 31 December, 2001 and 7 February, 2003.

Their arrests were witnessed by officers from the US Computer and Technology Crime Hi-tech team, which flew in from southern California.

At the time they were accused of being part of an international hacking group calling itself THr34t-Krew which created an internet worm to infect computers across the world.