ATHENS -- Instead of being obsessed with keeping illegal immigrants out, Europe should focus on drawing legal workers into its graying societies and sluggish economies, international experts said on Thursday.

They urged European Union leaders to see immigration as an opportunity, rather than being driven by public demands for sealed borders to hold back tens of thousands of illegal migrants trying to enter the wealthy 15-nation bloc.

The 150 leading migration experts and policymakers at a conference hosted by current EU President Greece, said politicians had to face up to the realities of Europe's economies and labor markets where key roles were played by workers from countries such as Iraq, Afghanistan and Turkey.

"The economy needs immigrants, but society does not -- at least this is how things appear," said Guido Bolaffi, director at the Italian Ministry of Labor and Social Affairs.

Europe will need an influx of 2.2 million immigrants a year from 2010 on just to prevent the level of employment from falling, EU statistics show.

Demographers and economists at the conference said immigrant workers were an important part of many European economies and the continent would need them even more as societies grew older and the working population shrank, Reuters reported.

While politicians recognize the need to attract high-skilled workers to fill labor shortages, the experts said those in low-paid service sector jobs also play a vital role.

"You are hearing that Europe needs high-skilled migrants but Europe also needs low-skilled migrants and it's going to get both," John Martin, head of the employment, labor and social affairs divisions at the OECD.

"If we expelled all of the illegal workers tomorrow we would have a significant problem in terms of meeting the demand for labor in a number of sectors and many people would be extremely unhappy," he added.