Vienna - A demographic gulf has opened up in Europe since the fall of the Iron Curtain, with migration behind a population decline in many eastern European countries, according to a new report.
While the population grew by 12 percent between 1990 and 2017 in the 15 oldest EU member states -- rich western countries -- it fell by an average of seven percent in the EU's 13 newer, and poorest, member states.
"While fertility rates in eastern Europe are no longer distinct from those in the West, population movements divide the continent in two," Tomas Sobotka -- a researcher from the Austrian Academy of Sciences who led the study -- said on June 22.
Almost all the former Eastern European and non-EU countries recorded a negative natural balance, the difference between births and deaths, over the 27-year period.
Net migration accounts for most of the decline in population, which fell by 27 percent in Latvia, 23 percent in Lithuania, 22 percent in Bosnia and Herzegovina, 19 percent in Bulgaria, 15 percent in Romania and 13 percent in Croatia.
In contrast, the majority of Western European countries recorded both a positive natural balance and a large influx of migrants.
- Ageing population headache -
Only in Ireland, whose population increased by a record 36 percent, and France, by 18 percent, did the higher number of births account more for the population increase than migration.
Also bucking the trend was Germany, whose population rose by only 4 percent since 1990.
While the natural balance has been negative, net migration has remained well below the average of other countries, despite the controversial arrival of more than one million asylum seekers since 2015.
The UK's 15 percent population growth was equally supported by immigration and natural increase.
Net migration in Russia helped to level out a natural balance down by 10 percent.
Europe has seen its population increase by eight percent to more than 510 million people, but with only 246 million people of working age the figure could "stagnate or even decline in the next few years," according to the OAW.
The ageing population poses a demographic headache for governments, with fewer taxpayers supporting a growing army of pensioners.