The contingency plans will cover key sectors of the economy such as telecoms, financial services, electricity generation, transport and broadcasting. They will also include Whitehall departments, particularly those responsible for large budgets and the payment of benefits to the unemployed, sick and elderly.
Other industries, such as process plant and the chemicals sector may also be drawn into the contingency planning because of fears of the threat to safety and industrial production resulting from wide-scale computer shutdowns.
The existence of the plans emerged yesterday as a new initiative was launched to tackle the Year 2000 computer threat. Don Cruickshank, chairman of the Millennium Bug Campaign, warned that while awareness of the problem was high, "very few" companies had so far acted to update their computer systems.
The problem stems from the inability of computers to recognise the change to years beginning with the number ''2''. There are fears that airline computers, traffic lights, hospital equipment and credit cards will not function properly, resulting in chaos on an unprecedented scale.
Estimates of the cost of adjusting the world's computers range from pounds 20bn to pounds 50bn. But Mr Cruickshank admitted yesterday: "I do not know how widespread the problem is going to be come 31 December, 1999. I do not know how much it is going to cost."
He also defended the comparatively tiny sums of government money being put into the campaign, even though Mr Blair described the threat as "one of the most serious problems facing British business and the global economy today".
Mr Cruickshank, who will put in one day a week, is pressing for an increase in his budget from pounds 1m a year but when the campaign is fully operational it will have a staff of only 10. At the moment it has an acting director, Dr Ian Eddison, who has been drafted in from the information technology industry.
The campaign will focus on giving industry, particularly small and medium- sized companies, advice on how they can solve their computer problem.
Once a company is confident its products are "millennium compliant" they will be encouraged to display a "Millennium Safe" logo (pictured below), although Mr Cruickshank stressed this would not mean any product or supplier would be government-approved. The campaign will also involve in-depth private market research to test how quickly the message is spreading. A total of 1,000 companies will be surveyed every quarter for the next two years.
Mr Cruickshank said one of the biggest areas of concern was the supply of sufficient numbers of IT specialists to deal with the problem. He also delivered a warning that as these skills became more scarce, companies would be charged more and the scope for cowboy operators to enter the market would increase.
Within the Government, each Secretary of State will be responsible for ensuring his or her department is millennium safe. A Cabinet committee chaired by Margaret Beckett, President of the Board of Trade, has also been set up to oversee the campaign and held its first meeting last night.