By Steve Scherer
ROME (Reuters) - The five million foreigners living in Italy pay 620,000 people's pensions, a study published on Thursday said, highlighting a potential benefit of Europe's biggest wave of immigration since World War Two.
The number of permanent foreign residents has doubled in the past decade and is climbing because Italy is on Europe's frontline of the migrant exodus from war and poverty in Africa, Asia and the Middle East.
Italy has taken in more than 136,000 seaborne migrants already this year, with almost 100,000 now living in immigration centers that the state will spend 1.16 billion euros running in 2015, according to the Interior Ministry.
The cost of providing migrants food and shelter has been a springboard for some opposition political parties, like the Northern League, who argue that the government treats migrants better than Italians.
But the Leone Moressa Foundation's annual report on the "economy of immigration" says that immigrants contributed 125 billion euros ($141.46 billion) to the economy last year, and that foreign workers gave more in taxes and welfare payments than the state spent on migrants.
"If the country wants to keep growing in the future, it cannot do without this new generation" of immigrants, lawmaker Khalid Chaouki said at the study's presentation.
Chaouki, a member of Prime Minister Matteo Renzi's Democratic Party, was born in Morocco.
In 2013, almost 2.2 million foreign workers paid 10.3 billion euros in welfare contributions, enough for 620,000 pensions, and there were than 632,000 businesses owned by immigrants.
And the immigrant population is projected to grow, the study said. Almost 12 percent of Italians are over 75 years of age, while only 1 percent of foreign residents are over 75. Last year fewer babies were born than in any other year since the formation of Italy's modern state in 1861.
Now at about 8 percent, the number of foreign-born residents living in Italy will reach almost 20 percent in 2050, the study projected.
Working mostly in the services industry, immigrants earn far less than locally born workers, the study said, earning an average of 13,180 euros per year, more than a third less than the average Italian salary.
(Reporting by Steve Scherer)