The number of immigrants registered as living in Spain has increased more than sixfold over the last 10 years, figures released by its National Statistics Institute have revealed.
Some 5.6 million non-Spaniards were registered as living in the country last year, accounting for 12% of the population, an increase of 400,000 on 2008.
Immigration helped the population reach 46.7 million in 2009, up from 40.5 million in 2000 when the country had just 924,000 immigrants officially registered.
At the beginning of the 1990s the population was made up almost entirely of Spaniards, with immigrants accounting for less than 1% of residents. But the past decade has seen an influx from around the globe, mostly from other European countries, South America and north Africa.
Joaquín Arango Vila-Belda, professor of sociology at the Complutense University of Madrid, said immigrants had occupied half of the jobs created in Spain between 2000 and 2008. He said: "Immigrants have arrived in their millions largely because of the availability of new jobs in Spain.
"Many of the 5m jobs created here between 2000 and 2008 were in sectors favourable to immigrant workers, such as construction, the hospitality industry and care."
Forty per cent of immigrants now living in Spain came from other EU countries, notably Romania, with 759,000 registered, and the UK, with 356,000.
Another 1.6 million came from South America and 902,000 from Africa, more than two-thirds of those from Morocco.The figures are taken from municipal registers of residents around the country and are released each year by the National Statistics Institute in Madrid.
Immigration has become a topic of political debate in recent weeks as Spain's economic crisis has deepened.
Unemployment reached 19% last year, almost twice the average for the euro zone, with a record 4 million out of work.
Last month Alicia Sánchez-Camacho, the leader of the People's Party in Catalonia, called for stricter limits on immigration and said the topic will play a leading part of her campaign for elections in Catalonia later this year.
And last month the town hall in Vic, 45 miles north of Barcelona, sparked outrage by attempting to ban illegal immigrants from the municipal register.
The move would have prevented illegal immigrants from claiming health care and education.
Unions say 43% of Vic's unemployed are foreigners, while around a quarter of residents are foreigners.
The controversial proposal in Vic, and a similar one in the Madrid suburb of Torrejón de Ardoz, wereboth dropped after receiving widespread publicity.
There are strong indications that the economic crisis is leading to a reduction in immigrants, who have been hit worse by rising unemployment than Spaniards.
Professor Arango Vila-Belda said the number of immigrants arriving in Spain had begun to slow dramatically in the latter part of 2009 because of rising unemployment.
