A computer hacker who helped spread a global virus has been freed from a six-month prison sentence.

Andrew Harvey, 24, of Sherburn Village, Co Durham, successfully appealed after London's Court of Appeal received a letter outlining family problems.

Two Court of Appeal judges said the sentence was being reduced as a matter of mercy.

But they stressed the sentencing by the judge at Newcastle Crown Court in October was not being criticised.

Harvey and Jordan Bradley, 22, of Darlington, were jailed after they admitted conspiracy to cause unauthorised modification of computers with intent, between 31 December 2001 and 7 February 2003.

Harvey was jailed for six months and Bradley for three months. Bradley did not appeal against his sentence.

On Friday, Mrs Justice Rafferty, sitting with another senior judge, stressed the sentencing carried out by Judge Beatrice Bolton at crown court was "unimpeachable".

She said: "She properly directed herself. She made no errors. The sentence cannot be criticised and we do not criticise it."

But she said the court could not remain untouched by the contents of the letter.

"As a matter of clearly expressed mercy, and for no other reason, we quash the sentence of six months and substitute one of two months which, for the avoidance of doubt, is intended to secure this appellant's immediate release."

Newcastle Crown Court heard that no great damage or destruction was caused by the worm, although it did have the capability to cause widespread disruption.