Deutsche Bank chairman Josef Ackermann

Dr Ackermann will be tried in a German regional court for breach of trust in connection with huge bonus payments made to executives at Mannesmann on the completion of the deal.

Dr Ackermann was a member of Mannesmann's supervisory board at the time of the takeover.

"Senior management remains convinced that Dr Ackermann has at all times acted honourably and professionally and believes the case against him is misconceived," a spokesman for the bank said.

The bank added that Dr Ackermann had the full support of management and the supervisory board, and ruled out the possibility of a resignation.

Dramatic

Prosecutors have been investigating the size of bonuses paid to Mannesmann managers at the end of the takeover battle for more than two years.

Former Mannesmann boss Klaus Esser himself is also under investigation, along with another member of the company's former supervisory board and the former chief of Germany's largest union, Klaus Zwickel.

Vodafone's takeover of Mannesmann was valued at $180bn and was the largest ever corporate merger at that time.

Some observers have described the controversy as one of Germany's most spectacular corporate dramas.