Australia’s four AA-rated banks collectively suffered a doubling in bad debt charges in their latest financial years but problem loans are forecast to decline in 2009-10 when earnings are set to rebound.

After earlier announcements from ANZ, Commonwealth Bank of Australia, and National Australia Bank, Westpac on Wednesday reported full-year net profits down from A$3.93bn to A$3.52bn. The 11 per cent profits decline came despite a sharp rise in impairment charges, up by A$2.09bn to A$3.29bn.