I should remind you that the transition does not end at 1201. Computer glitches could still crop up later

Canadian Y2K spokesman Guy McKenzie

Despite entering the year 2000 more dependent on computers than ever before, humanity witnessed no nuclear power plants melting down, no aeroplanes crashing from the sky, and electricity, water, transport and financial systems around the world continued to work normally.

The remarkable lack of problems amazed even those who were confident of a successful date rollover into the new millennium. "I would say I'm pleasantly surprised," said US Y2K trouble-shooter, John Koskinen.

The only potentially worrying events occurred at nuclear power plants in Japan. Radiation-monitoring equipment in Ishikawa failed at midnight but officials said there was no risk to the public. Alarms had sounded at another plant at the same time but no problems were found.

Russia's nuclear arsenal handled the date rollover

The most dramatic event, an announcement by the US military that it had detected the launch of three Russian missiles, turned out to be unrelated to the Y2K bug. Russian officials confirmed that the Scud missile launches were part of its ongoing conflict with rebels in Chechnya.

The global preparations for the millennium bug are estimated to have cost between $300 and $600bn and already questions have been asked as to whether this was necessary.

Worthwhile investment

"One of the questions you've begun to see surface is, 'well, has this all been hype?'" said John Koskinen, the US Y2K trouble-shooter.

The answer is no, he said, adding that preparing for Y2K had been "the biggest management challenge the world has had in 50 years."

Minor Y2K problems

US official timekeeper, the Naval Observatory, reported the date as 19100 on its website Japan - system collecting flight information for small planes failed Australia - bus ticket validation machines failed US - Over 150 slot machines at race tracks in Delaware failed Spain - worker was summoned to an industrial tribunal on 3 February, 1900 South Korea - district court summoned 170 people to court on the 4 January, 1900 Italy - Telecom Italia sent out bills for the first two months of 1900 UK - Some credit card transactions failed

"I think that we should not underestimate the nature of the problem that was originally there," he said.

Basil Logan is chairman of the Y2K Readiness Commission in New Zealand, the first industrialised country to see in the new millennium. He said: "New Zealand's investment in planning and preparation has paid off."

And in South Africa, the director-general of the government department overseeing South Africa's Y2K programme, Zam Titus, said: "Months of intensive preparations have paid off so far."

Matt Hotle, of the US technology consultants Gartner Group, agreed: "The reason we're in the position we're in is because we spent that money. Had we not spent this money, we would be facing worldwide calamity."

Not over yet

But despite the seemingly smooth transition into the 21st Century, experts are warning that there may still be problems ahead.

Any damage from the millennium bug need not be restricted to the moment the date rolls over, but could occur any time a computer mistakenly reads a year 2000 date.

Some websites showed the wrong date

The Gartner Group predicts that less than 10% of Y2K glitches will occur in the first two weeks of January, with 55% hitting over the rest of the year.

When offices begin to re-open and computers are turned back on, problems may start to appear.

"We do expect to see glitches, headaches, hiccups in the systems that support business, some of the accounting and billing systems, so these will create inconveniences next week," Bruce McConnell, director of the International Y2K Co-operation Centre, said in Washington.

Y2K makes no difference in Nigeria. We do not normally have light or water, so if we do now, it must be a bonus

Ayodele Adewale celebrating in Lagos

Bruce Webster, co-chair of the Washington-based Year 2000 Group, said he expects the biggest system failures to occur gradually, over a period of days and weeks. Even so, he downplayed the risk,

"Most Y2K errors are pretty dull," he said. "A program stops working or it makes a bad calculation. None of this means planes falling out of the sky or nuclear meltdowns."