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.

The former chancellor's comments come after the CDU put forward a proposal which was supported by the far-right AfD.

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.