Ruud Koopmans claims than no Western country has managed to successfully integrate Muslims.
"Muslims are much worse at integration than other groups of migrants, and there is no doubt that in most other groups of migrants, we see great progress from one generation to the next. Although it's not completely absent in Muslims, the change is much slower," he told Danish newspaper Berlingske recently.
Around 65 percent of the Turkish and Moroccan Muslims in six European countries consider religious rules to be more important than the secular law of the country in which they live.
Muslims consider themselves separate from other non-Muslim groups, and refrain from broader interaction with those outside their religion.