The chief executive of Switzerland's UBS bank says he won't resign over the $2 billion (SFr1.75 billion) loss incurred by a rogue trader revealed on Thursday.

Oswald Gruebel told the Swiss German-language newspaper Sonntag that calls for his resignation were “purely political”.

“If you ask me whether I feel guilty, the answer is  ‘no’,” he told the Sunday paper, while saying that he was responsible for everything that happens in the bank.

“When someone decides to act with criminal energy, you can’t do anything about it. This will always exist in our job,” he added.

Kasper Villiger, the chairman of the UBS board, told the Neue Zürcher Zeitung newspaper on Saturday that he was convinced the management of the bank had succeeded in bringing its risk management and monitoring system into line with today’s requirements.

“The fact that such a thing can nevertheless happen shows that there are still gaps which need to be closed,” he said.

The trader who allegedly made the unauthorised deals appeared in court in London on Friday, and was charged with fraud and false accounting.

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