SHANGHAI, Aug 6 (Reuters) - S&P Global has downgraded the ratings of heavily indebted developer China Evergrande Group and its subsidiaries, citing an escalating risk of non-payment of debt. S&P downgraded Evergrande and subsidiaries Hengda Real Estate Group Co Ltd and Tianji Holding Ltd to “CCC” from “B-” and lowered the long-term issue rating on U.S. dollar notes issued by Evergrande and guaranteed by Tianji to “CCC-” from “CCC+”, the agency said in a statement on Thursday evening. (Reporting by Andrew Galbraith; Editing by Muralikumar Anantharaman)