An expensive campaign to boost Germans' low self-confidence has backfired after it emerged that its slogan was first coined by the Nazis. The €30 million ($48 million) Du Bist Deutschland (You Are Germany) project was meant to inspire Germans to stop moaning and do something for their country.

But now a historian from Ludwigshafen has provoked an uproar with his discovery that the same Du Bist Deutschland cry was used at Nazi rallies in the 1930s. Stefan Morz found photographs of a 1935 Nazi convention in which soldiers display a banner reading, in gothic script, Denn Du Bist Deutschland (Because You Are Germany).

The slogan was topped with the head of Adolf Hitler.

"Every time I see the slogan Du Bist Deutschland I am reminded of this rather disturbing parallel with the past," Mr Morz said.

Researchers are now trying to discover how widespread the slogan was, even if most agree it was not one of the Nazis' official mantras. Its intended effect then is believed to be similar to that of the modern version: "You have the potential to make this country great once again."

The backers of the modern campaign, several blue-chip media companies, expressed shock at the discovery but quickly distanced themselves from the Third Reich connection.

Indeed, one of the campaign's aims is to release today's Germans from the collective guilt and depression they still feel about the Nazi era, they said. The project's image has now been battered by that same legacy.