The population of Muslims in Western Europe has been steadily rising in recent decades, largely due to immigration from the Middle East, South Asia and North Africa.

In Southeastern Europe, much of which once formed part of the Ottoman Empire, Muslims have been present for many centuries, but they are a relatively new phenomenon in the western part of the continent.

On the whole, Muslim’s represent about 5 percent of the population of the EU 27.

Far-right politicians in Europe have long warned that the Muslim numbers will continue to grow due to higher birth rates. Marine Le Pen, the head of France’s anti-immigrant National Front party, who openly discusses the rising number Muslims in France, could conceivably win next year’s presidential election, according to polls.

While the percentage of Muslims as part of the overall population of western European nations are in single digits, a 2009 study by the Telegraph newspaper in the UK estimated that by 2050, Muslims will account for 20 percent of the European Union’s populace. Long before that, Britain, Spain and The Netherlands will reach and surpass that figure.

In large urban cities, Muslims already account for a significant portion of the population For example, it is believed that one-fourth of the residents of Brussels, Belgium are Islamic. Moreover, at least three of Brussels’ 19 sections already have Muslim majorities.

Here are the nations of Western Europe with the largest Muslim populations (by percentage). Data comes from Islamicpopulation.com and are as of 2008, so they are likely to be somewhat conservative estimates:

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