German chancellor Angela Merkel says her country's attempts to build a multicultural society have utterly failed. Mrs Merkel told a conference of young members of her Christian Democrats party in Potsdam that allowing people of different cultural backgrounds to live side by side without integrating had not worked.She said immigrants should learn German in order to get by in school and have opportunities on the labour market.Anyone who does not immediately speak German, she said, is not welcome. The comments are the latest in an increasingly heated debate. Opinion polls indicate that there is much support for those who are uneasy about immigration.