By Danny Wood
BBC News, Madrid
Spain's National Institute for Statistics has released preliminary figures that show a dramatic increase in the country's immigrant population.
Spain has launched an amnesty for 800,000 immigrants
The number of foreigners living in Spain has nearly quadrupled over the last five years.
No other European country has experienced such a rapid rise in its number of immigrants.
In 2000, there were about 900,000 immigrants registered as living in Spain. Now there are 3.5 million.
It is an increase of almost 400%, and that number could be much higher.
Hundreds of thousands of Europeans and illegal immigrants living here do not register with the authorities. But it is the increase that is dramatic, not the actual number of foreigners living here.
Officially, immigrants now represent 8% of the country's population of nearly 44m people. That percentage is nothing out of the ordinary in the European Union.
About 10% of Germany's population for example consists of immigrants. The release of these figures comes as leading think-tanks call for a new policy towards immigration.
Earlier this week, Spain's government started the process of granting legal amnesty to up to 800,000 undocumented immigrants.