Embattled Josef Ackermann is reportedly on the verge of stepping down from the Siemens board just weeks after resigning as chairman of Zurich Insurance Group in the wake of late Chief Financial Offer Pierre Wauthier's suicide.

Ackermann, who is a former chief executive of Deutsche Bank, is on the verge of quitting his deputy chairman role at German engineering giant Siemens, an anonymous source with knowledge of the situation told Reuters. Neither Ackermann nor Siemens commented.

He left the board of insurer Zurich in August after his colleague Wauthier's suicide, which has been linked to the pair's fraught working relationship after it was referenced in the CFO's final note before he took his life.

The banker, who was once one of world's most influential financiers, released a resignation statement saying that he believed Wauthier's family held him partly responsible for the suicide, though he dismissed any allegations as "unfounded".

Separate reports in the Swiss press, citing sources who have purportedly read the suicide note, suggest Wauthier had written that it was difficult to work with Ackermann, including one incident of a "particularly hurtful" conversation between the two men.

After Ackermann's resignation, Zurich bosses launched an internal investigation to see if Wauthier had been placed under any "undue pressure" ahead of his tragic death.

"Let me be absolutely clear, we, meaning the board and management of Zurich, take corporate culture and behaviour very seriously," said Tom de Swaan, acting chairman at Zurich when he announced the probe in a conference call with concerned investors.

"In addition, from my own personal perspective, I am not aware of any behaviour that would be considered inappropriate in a board setting."

When quitting, Ackermann said he was trying "to avoid any damage to Zurich's reputation".

"I have reasons to believe that the family is of the opinion that I should take my share of responsibility, as unfounded as any allegations might be," he said, adding that the death of Wauthier has "shocked" him.

Ackermann remains on the boards of Royal Dutch Shell and Investor AB.