The population of Northern Ireland has jumped by 0.8 per cent to 1.7 million, figures released yesterday show.
The rise is 0.2 points ahead of the rise in the UK as a whole which now has a total population of more than 60 million for the first time, up from 42 million in 1911.
England's population grew by 0.7 per cent, Scotland was up 0.3 per cent and Wales 0.2 per cent.
Statistics from the Office of National Statistics (ONS) compiled for June 2005, but only just made public, show that a rising birth rate, falling death rate and migration from eastern Europe and the accession states of the European Union account for the growth in the North's population.
It was the biggest annual rise since 1962.
The UK is now the fifth most densely populated member of the OECD, well ahead of the Republic which is in 21st place.
Forecasters at the ONS predict that the North's population will rise by about an eighth in the course of the next 20-25 years.
Data showed 608,239 people aged under 25 lived in Northern Ireland. There were 22,611 births between mid-2004 and last year, and the survey recorded 202,678 people aged over 60.
Prof Bob Osborne of the University of Ulster's Social Policy Research Institute said the trend was likely to continue as the European Union expands.
"We have got more births than deaths across all areas of Northern Ireland," he said.
"We are having some of the largest in-migration in Northern Ireland of workers from the EU accession states. Historically that is the major change.
"Another reason for the gap is because in England a large number of people are leaving in their 50s and 60s and migrating to warmer climes. That isn't happening here in the same way."
Scotland is desperate to entice migrants to join its labour force, he said. But the major influx from other EU states had opted for Northern Ireland.
Many of these were well qualified and working at levels well below them. But they were compensated in this by earning more in the North than they could have done at home.
He added: "We don't know how permanent that may be, some may stay but others may earn some money and then go home. A lot of these people are vastly over-qualified for the work they do and yet the pay is still better than they could get at home. The peace process and economic improvements also make Northern Ireland a more attractive place to live."
A further significant rise in the numbers of migrants arriving in the UK from eastern Europe and new EU member states is expected in figures compiled by the Home Office in London next year.