Credit Suisse chief executive Tidjane Thiam has resigned amid a power struggle which followed a spying scandal at the bank.

The French Ivorian is stepping down after five years at the Swiss bank just months after it emerged that two former employees had been placed under surveillance.

Mr Thiam said he did not know the spying was taking place,

Credit Suisse's board backed chairman Urs Rohner for leading it "commendably during this turbulent time".

The BBC’s economics correspondent Andrew Walker says the scandal has shaken the rather conservative world of Swiss finance

Mr Thiam is something of a star in the financial world, he says.

He was born in Ivory Coast and spent part of his career in government there, but his international fame came from European finance, culminating in his appointment as chief executive of Credit Suisse.

The surveillance scandal initially came to light in September when a probe found the bank's former chief operating officer, Pierre-Olivier Bouée, had hired private detectives to track its former head of wealth management, Iqbal Khan.

Mr Thiam will leave on 14 February and is being replaced by Thomas Gottstein, who is head of the bank's Swiss business.

In a statement, Mr Thiam said: "I had no knowledge of the observation of two former colleagues.

"It undoubtedly disturbed Credit Suisse and caused anxiety and hurt. I regret that this happened and it should never have taken place."