Mr Jenkins, who took over as chief executive in August, told MPs he repeatedly raised concerns with the board and Mr Diamond over the culture at the bank and that “actions” were needed rather than words.
In a tense hearing with the Parliamentary Commission on Banking Standards, Mr Jenkins assured MPs he was taking action to address the “aggressive” and “self-serving” culture under Mr Diamond.
He said the bonus pool for 2012 had already been “substantially” reduced following a scandal-hit year that saw the bank’s reputation battered by the Libor rate-rigging affair.
The group added that today’s hike in provisions for compensation for mis-selling of payment protection insurance (PPI) and interest rate swap products to small businesses had specifically resulted in a “material” cut to the bonus pot.
Barclays revealed earlier it was setting aside a further £600 million for redress to cover mis-sold payment protection insurance, taking the total to £2.6 billion.
The bank will increase its provision for interest rate swap compensation by £400 million to £850 million in the wake of the City watchdog’s recent report on mis-selling of the complex financial products.
Mr Jenkins said last week he would waive his bonus for 2012 after a “very difficult” year for the bank.
Barclays has yet to reveal how much its overall 2012 bonus pool will be, but is expected to give details alongside the company’s annual results next Tuesday.