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 rejected asylum-seeker spills over into an election campaign in which he is the front-runner.

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

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.