Germany's education minister and a close ally of Chancellor Angela Merkel was fighting for her political life Wednesday after being stripped of her doctorate for plagiarism seven months ahead of elections.
Annette Schavan vowed to launch a legal battle against Duesseldorf University's ruling on her thesis, "Person and Conscience", written 33 years ago, amid opposition calls for her to resign.
"I will not accept the decision by the University of Duesseldorf and will file a lawsuit against it," she said in a brief statement in South Africa where she is on a five-day visit.
She said she planned no further immediate statement as it had now become a legal dispute.
Schavan, a member of Merkel's conservative Christian Democrats (CDU) and a confidante of the chancellor who in September will fight for a third term in office, has received Merkel's backing since the claims emerged.
She is not the first German minister to run up against plagiarism claims.
In 2011 Karl-Theodor zu Guttenberg, then the most popular figure in Merkel's cabinet, resigned as defence minister after his doctorate was rescinded for plagiarism, earning the aristocrat the nickname "Baron Cut-and-Paste".
Later that year, Silvana Koch-Mehrin, a German member of the European parliament, was stripped of her doctorate after an enquiry found that "substantial parts" of her 2000 doctoral thesis were copied from others.
Great store is set by the use of doctorate titles in German society.
Schavan, 57, who is also minister for research, has contested the claims since they were made public around nine months ago and has stressed that when they first emerged, she telephoned the university to ask that they be looked into.
A 15-member body in the philosophy department decided late on Tuesday by 12 votes to two and one abstention to withdraw Schavan's title after study of her thesis revealed "to a significant extent" the inclusion of unidentified verbatim sections of other text.
It found that she had "systematically and deliberately" passed off the work of others as her own without sufficient sourcing.
The opposition Social Democratic Party's chief whip Thomas Oppermann said Schavan must step down because she was an unsuitable example for young Ph.D. students who have to stick to academic rules.
If not, "that is the proof that this government has a defective relationship with the values of our society," he said.
But Schavan has received backing from members of her party, including deputy leader of the CDU parliamentary group Michael Kretschmer who called the university's procedure "a charade".
Bild daily commented that until now Merkel had stood firmly by her education minister. "However for her too, a limit may have now been reached. Annette Schavan is clever enough to recognise this and to herself accept the consequences -- resignation.
"There's no alternative for her."
The Stuttgarter Zeitung said that although it was possible Schavan could win her legal battle, "her credibility and effectiveness as a minister are from now so badly damaged that she should cede office".
Last month Merkel's spokesman Steffen Seibert told reporters that the chancellor had "complete confidence" in Schavan's work as minister.