Attempts to build a multicultural society in Germany have "utterly failed", Chancellor Angela Merkel says.
She said the so-called "multikulti" concept - where people would "live side-by-side" happily - did not work, and immigrants needed to do more to integrate - including learning German.
The comments come amid rising anti-immigration feeling in Germany.
A recent survey suggested more than 30% of people believed the country was "overrun by foreigners".
The study - by the Friedrich Ebert Foundation think-tank - also showed that roughly the same number thought that some 16 million of Germany's immigrants or people with foreign origins had come to the country for its social benefits.