The former chief of Britain's banking watchdog said he was "going to do what I do best" and drive operational change at Barclays (LSE: BARC.L - news) when he assumes his role as the bank's head of compliance this month.
Sir Hector Sants, who received a knighthood in the recent New Year Honours list, was appointed by the banking giant in December.
He will report directly to Barclays chief executive, Anthony Jenkins, and will join the bank's executive committee as it attempts to recover from a raft of recent scandals that have tarnished its reputation.
The appointment, which came months after the 56-year-old resigned as head of the FSA, was received with scepticism from some corners, given the British regulator's role in investigating Barclays for manipulating key global borrowing rates, resulting in fines on the bank of nearly £60m.
"Unless institutions like Barclays reform themselves dramatically, we'll have these problems again," he said, speaking to the Parliamentary Commission on Banking Standards on Thursday.
"These banks have got to change and one key issue that's got to change is the culture. If I can do that I believe I'll have made a good contribution."
His comments came as he appeared before MPs and Lords in parliament to face questions on the FSA's investigation into Libor-rigging at UBS (Berlin: UBRA.BE - news) , a probe which resulted in the regulator's largest ever fine of £160m.
He was joined by the FSA's ex-director for the banking sector Thomas Huertas and Tracey McDermott, who still works at the regulator as director of enforcement and financial crime.
Sir Hector defended his appointment to sceptical commission members, insisting there were no ethical question marks over his working at Barclays having had access to competitors' accounts as head of the FSA.
He said his taking up the role fitted with a vision of seeing banks transform from the inside after earlier contending that the stronger regulation of the new Financial Conduct Authority alone would not be enough to prevent further scandals engulfing the financial world.
Speaking after the announcement of Sir Hector's appointment in December, Mr Jenkins said: “I can think of no more suitably qualified person than Hector Sants to take on these challenges."