Deutsche Bank co-chief executive Juergen Fitschen has expressed regret over a phone call he made to a senior German politician following a raid at the bank's offices last week.

Fitschen told daily Frankfurter Allgemeine Zeitung in an interview published on Wednesday that he wanted to "expressly apologise" if people thought he tried to exert political influence on a legal case.

The 64-year-old said that he called Hesse state governor Volker Bouffier to express his "deep dismay" at the impression that the raids by 500 officers a week ago would make abroad.

Fitschen and CFO Stefan Krause are among 25 people being investigated for tax evasion, money laundering and attempted obstruction of justice in trading of carbon emission certificates.