The attack came from a former senior adviser to the Cabinet on information technology who now heads Taskforce 2000, a millennium bug consultancy backed by 20 blue chip companies. Ministers are becoming increasingly concerned about the problem as a survey showed that just two out of five British companies were making adequate preparations.
Robin Guenier accused Tony Blair of doing a U-turn on the problem. Mr Blair told the Commons recently that the situation was in hand, especially as far as larger companies were concerned, but he has become more pessimistic.
Mr Guenier said Action 2000, the official government body responsible for dealing with the issue, had adopted a "laid back" attitude to an "extremely serious problem".
Business did not full understand the implications and that was the fault of Action 2000. "The bug could threaten the livelihoods of millions of people," Mr Guenier said.
In his statement to MPs at the Commons, the Prime Minister said: "Time has very nearly run out for the firms that are behind. With under 10 months to go, they have two clear choices: use the time to beat the bug, or risk being beaten by it.
"The bug is biting now. One in 10 companies interviewed by Action 2000 has already suffered disruption caused by the bug. I strongly urge board directors, managers and employees alike to ensure their firms, their jobs and their livelihoods are safe from the bug."
Action 2000 said too many companies were "woefully behind" in their preparations. Only 43 per cent were on course to have a trouble-free new year, according to the fourth wave of research by the organisation.
Disturbingly, about four out of the five businesses that believed they were ready, were not, said Gwynneth Flower, managing director of Action 2000. Such companies were being sent a poster, warning them of "impending doom", she said.
The study showed that progress by large companies, employing 250 or more had been "too slow" in the past quarter. Action 2000 claimed at the end of last year that most big organisations were taking the appropriate measures.
Some 58 per cent of small to medium-sized businesses were now on course, compared with 49 per cent in the previous quarter - although the pace was not quick enough. Firms with between one and nine workers had progressed, with about one-third making the necessary preparations.
Ms Flower said that thousands of businesses were suffering from " bug tunnel vision".
She said that more than 80 per cent of companies thought the bug posed a serious problem, but less than half gave it a high priority. That was an "extraordinary" position to adopt and smacked of "amateurism", she said.
With just under 10 months to go, she warned that Action 2000 would be taking a tougher line and "naming and shaming" companies which did not measure up.
Ms Flower said: "Let's be clear, we are talking about the risk of severe disruption, or worse, of companies that fail to address their own vulnerability to the bug."
She said that enterprises had a legal obligation to ensure the health and safety of their employees and customers. Companies whose computer systems crashed, endangering life and limb, would be closed down by the Health and Safety Executive.
Ms Flower also warned that computer problems could mean a reduction in revenue, legal costs, a loss of customers and a breakdown of supply chains.