Chancellor Angela Merkel's defence minister has been stripped of his doctorate by the German university that awarded the title, after he admitted to flaws in a thesis that is the focus of a plagiarism row.
Karl-Theodor zu Guttenberg apologised 'from the bottom of my heart' to parliament, for errors he blamed on a busy workload.
|Apology: Karl-Theodor zu Guttenberg, the German defence minister, apologises for 'flawed' thesis in parliament
But the 39-year-old said yesterday he would not resign over the allegations and rejected accusations of plagiarism, insisting he had not deliberately deceived anyone.
Guttenberg, who has been for some time Germany's most popular politician and is sometimes named as a possible successor to Merkel, has been accused of copying parts of his PhD dissertation on constitutional law without correct attribution.
The scandal, dubbed 'Copygate', may damage the centre-right coalition ahead of six regional elections this year because the aristocrat has been one of the rare bright spots in Merkel's government.
Guttenberg has given the coalition a badly needed dash of glamour and topped voter polls for much of the last two years -- and a survey taken on Wednesday suggested his popularity was undimmed.
Guttenberg gave up his doctorate on Monday, admitting to an unintentional violation of academic standards. He attacked the media for a witch-hunt against him.
Bayreuth University formally stripped him of his title at a news conference chaired by its chancellor Ruediger Bormann, who had said such a decision was a matter for the institution alone. Bormann, who stopped short of accusing Guttenberg of plagiarism, said any thesis needed to include full references to source material and clearly identify passages taken from other works.
Guttenberg 'violated these requirements to a significant degree', Bormann said.
In a heated parliamentary exchange, Guttenberg had earlier answered questions for the first time from deputies.
'I was so arrogant to think that I could square a circle,' he said, referring to a busy workload with the dissertation while being a deputy in parliament and starting a family.
'I wrote a dissertation that was obviously flawed,' he said.
But analysts warn of dangers to him and Merkel over the affair because the plagiarism allegations go to the heart of his image as an honest and upright politician.
He denied, when asked by an opposition deputy, that he had used a ghostwriter to help him write the dissertation.
He also faced criticism from within his own party.
Norbert Lammert, a leader in Merkel's Christian Democrats (CDU) and president of parliament, had publicly scolded Guttenberg for not coming clean about 'the sloppiness' of his work.
The opposition Social Democrats renewed their calls for his resignation. Thomas Oppermann, an SPD leader in parliament, said Guttenberg was a cheat and getting special treatment.
© Daily Mail, London