Germany’s defense minister has found himself in a quagmire over allegations that he plagiarized portions of his doctoral thesis.

Karl-Theodor zu Guttenberg said he will refrain from using his academic title pending the outcome of an investigation of the charges by his former professors.

Opposition Social Democrat politicians have called for Guttenberg’s resignation as German media keeps hacking away at the minister, citing that his 2006 thesis at the University of Bayreuth was partially lifted from other sources.

“The doctoral thesis that I wrote is not a work of plagiarism,” Guttenberg, told reporters in Berlin. “It undoubtedly contains errors. But at no point was there conscious deception, nor were original sources consciously obscured.”

Guttenberg has been one of Germany’s most popular political figures and is closely associated with Chancellor Angela Merkel, who is supporting him. With an aristocratic Bavarian background, he has even been considered as a possible successor to the Chancellor.

Meanwhile Guttenberg has promised to cooperate with the university’s inquiry.

“Pending the result of this review, I will be happy to temporarily stop using my title,” he declared.