By Matthias Inverardi
DUESSELDORF, Germany, Jan 22 (Reuters) - A German university board voted on Tuesday to launch a full-scale investigation into plagiarism charges against Chancellor Angela Merkel's Education Minister Annette Schavan that could damage the conservative leader's re-election campaign this year.
The University of Duesseldorf's doctoral commission voted by 14-0 with one abstention to start an examination into allegations that parts of Schavan's 1980 doctoral thesis, which she wrote 33 years ago, were copied from the work of others.
Schavan, who is one of Merkel's closest allies in the centre-right coalition, has denied any wrongdoing and said she wrote her thesis with a clear conscience.
The probe could embarrass Merkel ahead of the September federal election, where the German leader will be attempting to win a third term.
"The board has discussed the facts in detail and voted with a secret ballot by a score of 14-0 with one abstention to open a full investigation," said university dean Bruno Bleckmann. The board will meet again on Feb. 5.
Last month, in a preliminary step, a faculty board voted unanimously for a full inquiry.
The accusations are similar to those that in 2011 brought down Merkel's defence minister and heir-apparent, Karl-Theodor zu Guttenberg, but could prove more damaging for the government only eight months before an election.
As Schavan is education minister, the case is a direct threat to her credibility, and opposition leaders have called on her to resign. Merkel has said Schavan has her confidence.
Schavan was among the first to condemn Guttenberg for plagiarising his PhD thesis, calling it "shameful". Schavan's thesis is entitled "People and Conscience - Studies on the conditions, necessity and requirements for formation of conscience today".
Allegations of plagiarism have dogged her since May and she asked the university to examine them. A report by its philosophy faculty found indications of a "plagiaristic approach" on 60 of the 351 pages, magazine Der Spiegel reported. (Writing by Erik Kirschbaum; Editing by Louise Ireland)