Conservative frontrunner Friedrich Merz of the Christian Democrats has reaffirmed his principled rejection of cooperation with the far-right Alternative for Germany (AfD), despite Wednesday's joint approval of a Bundestag motion on migration policy.

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.

Four weeks before Germany’s snap election, the political temperature is rising as the campaign shifts onto the contentious terrain of migration and Elon Musk steps up his support for the far-right AfD party.