Severely past-due loans climbed quickly at Bank of Queensland in the May 2011 quarter, rising by one third to A$460 million.Impaired loans increased by six per cent to $421 million.Loans 90 days or more past due have roughly doubled over the last year, the quarterly "pillar 3" disclosure for the bank shows.Impaired loans have trebled over the year.No doubt the floods in several regions of Queensland in early 2011 are the primary factor in the rise in problem loans.Structural factors are also at play, such as the depressed tourism industry (thanks to the high exchange rate). One quirk in the pillar 3 is that they appear to show the bank is expanding its assets at a rapid pace. Gross credit exposures at the end of May, at $75 billion, were 10 per cent higher than at the end of February. The bank has expanded the asset side of its balance sheet by 30 per cent over the last year, based on the measures used in pillar 3 reporting.Growth in residential lending was 18 per cent over the quarter (rising to $23.6 billion from $19.9 billion over three months), according to the quarterly report.Monthly data from APRA shows a much more measured, and apparently accurate, growth in footings, with home loans increasing less than two per cent over the quarter.