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.

Friedrich Merz, the leader of Germany's CDU/CSU conservative bloc which is leading polls ahead of the Feb. 23 vote, is keen to seize the initiative on migration policy, which has shifted sharply back into focus after an Afghan asylum seeker was arrested over deadly stabbings last week.

The CDU party chief, who leads in the polls to become the next chancellor, said he would collect votes from all parties to push his five-point migration plan through parliament despite Chancellor Olaf Scholz's strong opposition.

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.