Last year, while the country suffered its deep recession, it was discovered that the King was elephant-hunting in Botswana in the company of Corinna Zu Sayn-Wittgenstein, a German princess with whom he has been romantically linked and whose name has also appeared in documents related to the Urdangarin investigation.

FORBES: Bad Timing for a Royal Spanish Scandal

Mr zu Guttenberg is expected to survive a parliamentary inquiry, thanks largely to his soldierly sheen and his popularity with voters.

ECONOMIST: Germany and Afghanistan

Karl-Theodor zu Guttenberg, an aristocrat who lives in a Bavarian castle, admitted breaching standards but denied deliberately cheating.

BBC: German minister loses doctorate after plagiarism row

Rainer Arnold, defence expert with the opposition Social Democrats (SPD), told German media that if the accusations of plagiarism were found to be true, then Mr zu Guttenberg would lose all credibility "and a minister who's lost his credibility can't really work any more".

BBC: German minister denies plagiarism on PhD thesis

If it then decides to revoke the doctorate, that might present a problem for plain Mr or Baron zu Guttenberg, or whichever title he chose to use.

BBC: Karl-Theodor zu Guttenberg: Baron without a title

Mrs Merkel arrived early on Saturday in Kunduz, where Germany has a base, accompanied by Defence Minister Karl-Theodor zu Guttenberg and military Chief of Staff Volker Wieker.

BBC: Germany's Merkel makes unannounced visit to Afghanistan

This stood Mr zu Guttenberg in good stead when he suffered the first big reversal of a dazzling career.

ECONOMIST: Germany and Afghanistan

But when prospective sellers, including German Prince Michael zu Salm-Salm, checked, they learned Shapiro had no operations, no cash reserves and a pool of private stock of unpersuasive value, says Bowthorpe.

FORBES: Corkscrewed