ANZ NZ has reported a 33 per cent rise in its December 2013 quarter net profit as the late 2012 merger of its ANZ and National brands helped drive costs seven per cent lower and stronger economic growth helped reduce bad debt charges.ANZ NZ reported a statutory net profit of NZ$393 million in its December Quarter General Disclosure Statement, including a five per cent rise in net interest income to NZ$688 million and an 11 per cent rise in other operating income to NZ$241 million."The successful merger of the ANZ and National Bank brands and technology systems has enabled the business to continue growing deposits and lending, including market share growth in mortgages," ANZ said.Operating costs fell NZ$27 million to NZ$371 million in the December quarter from the same quarter a year ago.Charges for bad and doubtful debts turned into a credit of NZ$21 million after write-backs of previous provisions of NZ$28 million for non-retail lending.  The credit represented a NZ$63 million turnaround from a charge of NZ$42 million in the same quarter a year ago.Profit before credit impairments and taxes therefore rose by the lesser amount of 18 per cent to NZ$558 million. Lending rose 3.4 per cent to NZ$91.29 million, which was slightly below total bank lending growth in New Zealand of around 4.5 per cent for calendar 2013.