By Andrea Figueras and Ulrike Dauer

Deutsche Bank said that German prosecutors were searching its Frankfurt office as part of an investigation into some transactions that took place between 2008 and 2010 at Postbank.

The German lender said in a statement that the raid is related to transactions at its Postbank unit, which Deutsche Bank acquired in late 2010.

Deutsche Bank declined to elaborate on the nature of the transactions.

"Deutsche Bank is being searched as a third party in this matter and we are cooperating fully," it said Wednesday.