The head of Germany’s armed forces has called for an inspection of all army barracks after investigators discovered Nazi-era military memorabilia in a garrison, broadening a scandal about right-wing extremism among soldiers.

The discovery at a barracks in Donaueschingen, in southwest Germany, was made in an investigation that began after similar Nazi-era items were found in the garrison of an army officer arrested on suspicion of planning a racially motivated attack.

As a result, general inspector Volker Wieker ordered a wider search of barracks.

“The general inspector has instructed that all properties be inspected to see whether rules on dealing with heritage with regard to the Wehrmacht and National Socialism are being observed,” a Defence Ministry spokesman said.

Defence Minister Ursula Von der Leyen said the military must root out right-wing extremism.

“We are training people with weapons. It is right that there are higher standards for us. A ‘carry on’ attitude is out of the question,” she told weekly newspaper Bild am Sonntag.

Displaying Nazi items such as swastikas is punishable under German law, although possession of regular Wehrmacht items is not. However, von der Leyen said last week she would not tolerate the veneration of the Wehrmacht in today’s army, the Bundeswehr.

Ms Von der Leyen provoked criticism from a soldiers’ group last week when she criticised what she called “weak leadership” in the military after the officer’s arrest on suspicion of planning a racist attack.

On Thursday, she apologised for the tone of her criticism of the military over its handling of the racism case, as she sought to contain a divisive row in the build-up to national elections in September.

A preliminary report into the inspection of all barracks is due on Tuesday, with the final results on 16 May.