Chan, said to have risked causing a catastrophe, is the first person to be convicted in Hong Kong of criminal damage to computer files. The ruling will influence future sentences for computer crime.

His barrister, Gerard McCoy, SC, said Chan had no girlfriend and 'had only ever held hands with a computer'.

Mr Justice Saied said: 'What he did went far beyond holding hands. 'It is the duty of the courts to ensure they impose such sentences in cases which are likely to damage or have the potential to damage the trust and confidence others place in this city, that will deter similarly inclined from committing such offences.' But the court ruled the sentence passed on Chan at the District Court was too harsh.

The level of four years, adopted before reductions were made for mitigating factors, was too high, Mr Justice Saied said.

Chan was also entitled to a further discount because he had compensated one of Reuters' clients for its $60,000 loss.

The engineer, who has a master's degree in science, planted a command on computers used by five banking customers which caused financial information files to disappear.

He was driven by anger and revenge following a dispute with his boss.

Reuters was justified flying in experts from abroad to help limit the damage, Mr Justice Saied said.

The company estimated the cost of the operation at GBP108,000 (HK$1.34 million).

Mr Justice Saied noted that Chan's life in prison had been described as 'intellectual solitary confinement'.

But he said the discomfort he suffered was a direct result of his calculated crime and he deserved a prison sentence.