German conservative leader Friedrich Merz is set to take his hard-line immigration push to the next level despite a growing backlash over his move this week to force a resolution through parliament with backing from the far right.

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.

German election frontrunner Friedrich Merz succeeded on Wednesday in getting a motion passed in parliament that calls for a migration crackdown including the rejection of asylum seekers at the country's land borders.

Former German Chancellor Angela Merkel has issued rare public criticism of her successor as the country’s center-right leader, the front-runner in Germany’s election next month, for putting to parliament proposals for tough new migration rules that only passed with the help of a far-right party.

Former German Chancellor Angela Merkel criticised the leader of her Christian Democrats (CDU), Friedrich Merz, for drawing on support from the far-right to pass a motion in parliament, in a statement on Thursday.