Germany's main opposition leader vowed on Thursday to impose immediate border controls if he becomes chancellor, as expected, after elections next month, a day after an Afghan asylum seeker was arrested for a deadly knife attack targeting children.

Germany’s opposition leader has vowed to bar people from entering the country without proper papers and to step up deportations if he is elected as chancellor next month, as a knife attack by a reject

The conservative leader wants to impose strict border controls after knife killings in Aschaffenburg this week.

The conservative opposition leader tipped to lead Germany following next month's elections has promised far-reaching changes to border and asylum rules after a group of children were targeted in a deadly knife attack in Bavaria.