With 500 days to go to the Year 2000, experts said yesterday that it may already be too late for many companies to defuse the millennium computer time bomb.

According to the Gartner Group, a US high-technology consultancy, nearly a quarter of all companies worldwide have not yet started work on plans to solve Year 2000 programme problems. This means most of these organisations will effectively be unable to fix their systems in time.

The Gartner Group, which said last year that millennium bomb rehabilitation would cost between $300 billion and $600 billion worldwide, also said in the report published this month that only 50 per cent of companies that had projects to eliminate the bomb planned to test their corrected systems.