Any inference that there may be less explicit government support for banks in a crisis may warrant a cut in the long-term credit rating of five banks, Standard & Poor's believes.In a report on "Australia's Developing Crisis-Management Framework", S&P pointed to a "hypothetical rating impact" should the "government's willingness to support banks" be lowered to "supportive", under S&P's assessment, from "highly supportive".The scenario arises in the context of what S&P calls "contingency plans for domestic, systemically important financial institutions in Australia."Six banks - the four majors, Macquarie and Cuscal - have had recovery plans approved by APRA. All these include some element of "bail in" that could defer repayments to debt investors."Some of the changes being considered for Australia's banking regulation relate to crisis management could diminish the case for factoring in government support to banks' ratings at the level currently assessed," S&P said."Under such a hypothetical scenario, our opinion is that the ratings on the four Australian major banks and Macquarie Bank might be lowered by one notch," the ratings agency said.This would cut the ratings of the major banks from AA- to A+, and Macquarie's to A- from A.S&P does not expect any change to the long-term rating of A+ for Cuscal.