Commonwealth Bank chief executive Ian Narev says he has no plans to retrench any of the bank's 45,000 staff or send their jobs overseas.Narev said he had a strong commitment to continuous improvement in the business. "In the economic environment we are in we need to be a lot more productive," he said"But we believe the way to do that is not by taking a red pen and cutting things out. That approach does not deliver sustainable productivity improvement."The bank reported "flat jaws" during the December half, which means that income and expenses increased at the same rate.Analysts at yesterday's December half results briefing queried whether the bank could do more to reduce expenses by cutting its big information technology investment budget and rationalising the branch network. The bank's investment spend during the December half was A$647 million. A third of that went on its long-term core banking modernisation. Narev said investment in the project would start to tail off by the end of the year. "Once core banking tails off it frees capacity but we will not look to spend that money somewhere else."Analysts have been questioning the wisdom of continuing to invest in the branch network when demand for household and business finance is expected to remain weak and electronic services are being taken up by an increasing number of customers.Seven per cent of the bank's investment spending during the half went on branch refurbishment.Narev said: "We do talk a lot about technology but the reality is that the branch channel is critical."We are giving a lot of thought to how the role of branches is changing. We still have an appetite to invest there."Narev was unapologetic about the growth in staff numbers during the past year. In the past 12 months, staff numbers (full-time equivalents) grew two per cent, from 45,025 to 45,810."If the current weak trading conditions continue and revenue levels remain flat, the bank would look to operate with fewer people. But that would be achieved through natural attrition, which is about 3000 people a year."If revenue grows we still might have growth in FTEs," he said.He said the bank had achieved significant productivity improvements in mortgage processing, the call-to-fulfilment ratio in the Bankwest call centre and transaction processing in the investment operations.