A 99-year-old Holocaust survivor said on Thursday he would return his federal order of merit award to the German state in protest over a parliamentary vote in which support from the far-right was used for the first time to secure a majority.

Opening the door to leaning on support from the far-right is a gamble for Merz, who believes that his increasingly radical stance on migration will win back right-wingers who are tempted to vote for the AfD. But in so doing, he could risk losing support from the centre.

Protesters in Germany on Thursday rallied against the conservative CDU party to decry its cooperation with the far-right AfD in pushing through parliament a motion to demand a crackdown on immigration.

Germany's opposition conservatives won parliamentary approval on Wednesday for a proposal to drastically restrict migration with the help of votes from the Alternative for Germany (AfD), breaking a taboo on cooperation with the far-right.