She spoke out after an army lieutenant was arrested on suspicion of plotting a racist attack.

The minister said his superior officers had looked the other way and the army had an attitude problem.

But critics said she had offended every honest soldier.

The alleged plot was revealed last week, involving a 28-year-old soldier who had used a fake identity to register as a Syrian refugee in December 2015.

Franco A spoke no Arabic and is thought to have been planning an attack disguised as a refugee. It emerged he had expressed far-right views in an academic paper for a military academy in 2014.

Another soldier was arrested after being found with explosives.

Soldier posing as refugee 'planned attack'

Ms Von der Leyen has been defence minister since 2013 and is seen as a leading figure in Chancellor Angela Merkel's CDU.

Her initial criticism of the army's handling of the case was made on national TV on Sunday night and she followed it up with an open letter.

Apology demand

While the vast majority of soldiers behaved impeccably, she said the latest scandals were no longer isolated cases. She spoke of "a misunderstood esprit de corps" that had led superior officers to "look the other way".

The centre-left SPD's defence spokesman, Rainer Arnold, called on Ms Von der Leyen to apologise for raising questions about the whole army.

How could you explain such generalisations to soldiers serving in foreign countries like Mali who were having to deal with the toughest assignments with limited equipment, he asked.

"Nobody can understand why the minister, after three-and-a-half years in office, retreats to the stands, so to speak, and sweepingly condemns her own team," said André Wüstner of the armed forces union, the Bundeswehrverband.