Standard & Poor's has downgraded HSBC Bank Australia's credit rating, citing a review of the local bank's status as a subsidiary of the HSBC Group.In a statement issued yesterday, S&P said it had cut HSBC Bank Australia's long-term rating from AA- to A+, and its short-term rating from A-1+ to A-1.S&P said: "The group's disposal of entities elsewhere in the world has led us to reassess the extent to which HSBC Bank Australia is fully integrated with the wider group."It has changed its categorisation of the local bank from a "core" subsidiary to a "highly strategic" subsidiary. "It is not so full integrated that its operational linkages make it practically inseparable from the rest of the group," S&P sad.In response, HSBC Bank Australia issued a statement yesterday that said: "Australia has been a priority growth market for the HSBC Group since it outlined its group strategy to investors in May 2011 and this has not changed."