The secretary general of the Central Council of Jews in Germany, Stephan Kramer, said he found the decision not to include other religious faiths in the project beginning on Thursday "quite painful."

"It is like in school -- Ms Von der Leyen has failed, she did not pass the test," Kramer told the daily Abendzeitung in the southern city of Munich, adding that education on ethics should not be linked to a specific religion.

The Central Council of Muslims echoed the criticism. "In the interest of the neutrality of the state, it is absolutely imperative that other religions are invited," chairman Ayyub Axel Köhler told the same newspaper.

Von der Leyen, a member of Chancellor Angela Merkel's Christian Democrats and mother of seven, hit back at the complaints saying that the decision to invite the Roman Catholic and Lutheran churches to participate in the "Alliance for Upbringing" was just a beginning.

Von der Leyen on the defensive

"We made a first step with the two churches, but it is a start and others are invited to join this alliance," she told public broadcaster WDR.

She said a second stage of the program would begin later this year and that other religious organizations as well as family affairs associations and industry groups could then participate.

"The idea is that we should give more of a priority to values-oriented upbringing," she said, adding that the two churches had a wealth of experience in this area. They run 74 percent of kindergartens and thus have the structures to ensure a broad base, she said. Germany's culture is also based on Christian values, she said.

A heated debate about the state of German education and the integration of children from immigrant backgrounds resurfaced last month after reports of chaotic, violent conditions at a school in a working-class district of Berlin.