"We are in the process of improving the control systems," he said.
His comments came as a separate report charged that UBS had not only manipulated global interest rates, but had also tampered with Swiss franc interest rates for more than a decade.
UBS did not immediately respond to requests for comment. US, British and Swiss authorities last week hit Switzerland's largest bank with $1.5 billion in fines - the second-largest banking penalty ever - for massive misconduct in the setting of the Libor rate. That rate is used as a benchmark for global financial contracts worth about $300 trillion and affects financial products world-wide such as student loans and mortgages.
Both Weber and Ermotti stressed in Sunday's interview that Swiss investigators had found no indication top UBS executives were aware of the misconduct.
But Weber acknowledged that responsibility for the Libor scandal lay "not only with the people who committed crimes, but also with those who were tasked with supervising them," noting that people not directly involved in manipulating rates had also been fired.
The French-language daily Le Matin meanwhile reported in its Sunday edition that UBS had not only contributed to manipulating global interest rates on the dollar, the British pound and the yen.