A former Commonwealth Bank executive alleges he was bullied and sacked after blowing the whistle on a system that allowed staff to artificially boost their bonus pay by making false claims about introducing bank products to customers.

Timothy Richard Cradock was employed as an executive manager overseeing group strategy and international financial services and received a salary of $221,470 plus an incentive payment of $143,500 in his final year of work. His contract provided incentives potentially worth up to $205,000 in 2012. He was also general manager for migrant and multicultural, retail banking services.

CBA will apply a "servicing loading" of 20 per cent to all repayments on existing home loans and lines of credit held by customers. Credit:Michael Clayton-Jones

Mr Cradock is making a claim for compensation estimated at about $5 million plus interest and costs. The amount would be based on an actuarial calculation of the difference between what Mr Cradock's earnings might have been and what they are. The Commonwealth Bank strongly refutes Mr Cradock's statement of claim.

The statement of claim lodged in the Federal Court alleges Mr Cradock reported his discovery of the One Team Referral (OTR) electronic system to the executive general manager of retail sales and services, Lyn McGrath. The system allegedly allowed bank staff to make false claims about introducing services and products to potential customers, which then artificially boosted their bonus pay.