Members of the right-wing populist Alternative for Germany (AfD) have hardened their stance on Islam as they prepare for their upcoming party congress in Stuttgart.

"Islam is not a religion like Catholic or Protestant Christianity, but rather always associated intellectually with the takeover of a state," said AfD's Brandenburg leader Alexander Gauland in an interview with the newspaper "Frankfurter Allgemeine Sonntagszeitung."

The party's deputy leader, Beatrix von Storch (pictured), who last month was ejected from an EU parliamentary group for her position on immigrants, echoed Gauland's statement.

AfD: Islam a 'political ideology'

"Islam is a political ideology that is not compatible with the constitution," von Storch was quoted as saying in the same article.

The AfD is now calling for a ban on minarets, burqas and muezzins, the people who lead the call to prayer in a mosque.

Members of Chancellor Angela Merkel's Christian Democratic Union (CDU) have also criticized the burqa, the full veil worn by Muslim women, but haven't said Islam is incompatible with Germany.

Last month, the AfD had a strong showing in Germany's regional elections, coming in second behind the CDU in Saxony-Anhalt and taking double-digit percentages in two other states. The party's success has been attributed to growing concerns over the influx of largely Muslim refugees into Germany over the past several months.