SYDNEY, Feb 6 (Reuters) - National Australia Bank (NAB), the No. 4 lender by market value, on Monday reported a 1 percent fall in first quarter unaudited cash profit as costs grew faster than revenue.
NAB posted unaudited cash earnings of A$1.6 billion ($1.23 billion) for the quarter ended Dec. 31, down 1 percent from the same period a year earlier.
The bank said costs rose by 5 percent in part due to annual salary increases and higher redundancy costs, while revenue rose by 1 percent.
The ratio of 90-days past due and total impaired assets to gross loans rose to 0.90 percent at end-December from 0.85 percent at end-September 2016. NAB did not give a reason for the increase. It said its net interest margin was "broadly stable". ($1 = 1.3050 Australian dollars) (Reporting by Jamie Freed; Editing by Louise Ireland)