One in five people living in Germany now comes from an immigrant background, according to figures released on Thursday. They show that the minority community grew by more than 1.3% last year at a time when the overall population is falling.

Figures from the German Federal Statistical Office show that the number of people with immigrant backgrounds living in Germany increased by 216,000 from 2010 to 2011. Multiculturalism has been a fiercely controversial topic in Germany in recent years, engendering vigorous debate over the integration of immigrants, many of whom moved to the country in the 1960s as guest workers from Turkey. There are now 16 million people with an immigrant background living in Germany – 19.5% of the country's population.

Although Germans have discovered a greater affinity with their minority communities thanks to the exploits of football stars such as Mesut Özil and Sami Khedira, there have been a growing number of voices challenging the value of multiculturalism. This week, the mayor of Berlin district Neukölln, Heinz Buschkowsky, argues in a new book that multiculturalism has failed.

There is some evidence that the most recent rise in immigration has been caused by economic refugees from southern European countries as a result of the euro crisis. But the debate habitually falls back to the integration of the Turkish community, which represents the highest number of immigrants in Europe's biggest economy.

"Many politicians and policymakers see integration politics as a way to create a homogenised society rather than encouraging equal political and social participation for everyone in Germany – integration is well-intentioned but ill-implemented," said Gökçe Yurdakul, a social scientist specialising in diversity and social conflicts at Humboldt University in Berlin.

The issue has driven a wedge between Germany and Turkey in recent years, most notably when Christian Wulff, the then German president, was told by his Turkish counterpart, Abdullah Gül, that Germany should be doing more to help Turks integrate into German culture. This followed claims by the German chancellor Angela Merkel that multiculturalism had failed.

Some experts disagree, saying integration is already happening at a local level. "You can see that integration is happening through local initiatives and civil society organisations putting efforts into living together in a diverse society," said Yurdakul. However, the efforts were not reflected on a national level and politicians still had a long way to go.

"[These] policies are trying to get people equal access to labour markets, politics, education and healthcare, but on the other hand it's ill-implemented because it's used to restrict immigration in Germany."

Then there are those held up as successes of integration such as Özil, who is descended from Turkish immigrants and considered a national hero.

Younger people are starting to make an effort to reach out to the Turkish communities to integrate themselves with their neighbours. Marlene Schliepach, 26, is studying to become a kindergarten teacher and started learning Turkish two years ago in an effort to be able to talk to the children she will be caring for.

"I'm learning Turkish because I want to convey to my Turkish students that I, as their teacher, and as a German, value their language," she said. "Lots of teachers want to make them focus on only learning German. But integration has to go both ways."

Some, such as Tim Panhorst, 27, are learning Turkish because of family connections to the culture, but think it is important for Germans to attempt to reach out. "I wasn't really learning it from school, but from friends and relatives because my brother is married to a Turkish girl," he said.

"But when I meet Turkish people and speak to them in the language, my experience is that they are always glad someone German can. It's always a way of connecting, and in a positive way."

• This article was amended on 20th September 2012 to correct the figure of 1.3% relating to community growth in the first paragraph. It previously read 13%.