A report by the German Association of Cities recounts problems of illegal working, schoolchildren being unable to speak German and a rise in organised crime since the migrants arrived. Berlin, Hamburg, Dortmund and Hanover have seen a six-fold increase in economic migration from the two countries since 2006, which they say has left them struggling to cope. The report says cities are facing â€œsignificant costs as a result of this poverty migrationâ€. It calls on Chancellor Angela Merkel to provide financial assistance to help them deal with the strain under which the migration is putting them, the Daily Mail reported. â€œThe social balance and social peace is extremely endangered,â€ the report says.The warning comes amid fears in Britain that tens of thousands more Romanians and Bulgarians will come here each year after formal restrictions on the numbers of low-skilled workers from the two countries end next year. A report by the campaign group Migration Watch UK warned last month that up to 70,000 migrants could arrive annually from then. But Romaniaâ€™s ambassador, Dr Ion Jinga, has argued that Romanians are more likely to migrate to countries such as Spain, Italy and France because of linguistic similarities. An annual quota was imposed when Romania and Bulgaria joined the European Union in 2007, with the aim of limiting numbers to 25,000 a year in the UK. But under EU rules on free movement, a country cannot impose restrictions on the self-employed. There are already more than 90,000 Bulgarians and 159,000 Romanians in Germany but, as in Britain, they are not allowed to work legally until January 1, unless they declare themselves self-employed.