BERLIN (Reuters) - German opposition leader Friedrich Merz, tipped to become the next chancellor, said on Thursday he wanted to win back the lost trust of key allies and ensure Berlin is more assertive on the global stage in a speech laying out his foreign policy plans.

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

Friedrich Merz, the leading candidate for the chancellery in Germany's upcoming election, said a leaked briefing by Germany's ambassador to the United States heavily criticising Donald Trump was damaging to the German government's reputation.