This New Year's weekend could prove to be a litmus test of the troubles ahead as companies large and small find out whether digital systems that look ahead one year have been able to recognise the dreaded number, 2000.

But Action 2000, the government body set up to tackle the bug, says it will be some days before firms will be able to assess the impact of '99 and beyond.

April and the start of the new financial year has been pinpointed as "another critical point", according to spokesman Simon Hill. "We are calling it the bug that pervades, rather than a time-bomb which is misleading," he said.

Bug spreads

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He added that research carried out last November showed one third of 3,000 small- to medium-sized companies had already been affected by the bug.

An NHS trust discovered its advanced booking system could not process appointments made after December 1999, and Canterbury Cathedral had a similar problem booking tourist visits more than one year ahead.

New Year warning

On New Year's Day, the head of Action 2000, Gwyneth Flower, told BBC Radio: "We expect that from today onwards, incidents will occur because it is the first time many computers will have seen the year 2000 for real."

She said small and medium-sized firms were "still woefully complacent" and she said that not enough was being done.

Such dire warnings may be necessary but they have resulted in a kind of paranoia that has led some people to stockpile provisions for fear of a breakdown in the country's infrastructure.

They include university academics, council officials, business people and even an advisor to Action 2000's predecessor, Taskforce 2000. David Walton told the Sunday Times newspaper: "There might very well be some sort of disruption to the food supply and energy distribution. It makes sense to make provision."

Total systems breakdown

So while trying to ensure the nation's computers are fixed for 2000, the government also wants to allay fears of a total breakdown in the infrastructure.

It believes essential services will run with only a small chance of disruption, nine out of 10 larger organisations will fix their computers. Just in case, the armed forces will be on standby for emergencies.

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Nevertheless, remarks made by Action 2000's Ms Flower last month to the Observer newspaper that it would be wise to buy two weeks' of emergency supplies over the week-long millennium holiday did not help their case.

"Those remarks were taken out of context," said a spokesman. "We are categorically saying there is no need to stockpile."

Pessimists will take little comfort from the words of Margaret Beckett , the leader of the House of Commons who is also in charge of co-ordinating the government's response to the bug. She told BBC Radio that even if individuals and companies ensure they are bug-free, they still have to rely on the computer systems of others.