On Wednesday development minister Gerd Müller became the latest in a line of German ministers to face plagiarism allegations over their doctorate works.
The 58-year-old Christian Social Democrat (CSU) politician allegedly plagiarized a passage of his PhD thesis written in 1987 about Bavaria's political youth.
Plagirism investigator Martin Heidingsfelder told Bild newspaper there were errors in the passage. According to the Frankfurter Allgemeine newspaper, certain quoted passages were not correctly cited.
But Müller denied the allegations and described them as "incomprehensible".
His spokeswoman told Die Welt newspaper that the minister welcomed the investigation by the University of Regensburg’s ombudsman as it would provide clarity on the situation.
In February last year Germany’s education minister Annette Schavan quit over plagiarism of her doctorate thesis.
Her resignation followed that of defence minister Karl-Theodor zu Guttenberg who resigned in 2011 amid allegations he too had plagiarized his PhD work.