Sept 29 (Reuters) - Rating agency Fitch said on Wednesday it had downgraded the long-term foreign-currency issuer default ratings (IDRs) of Chinese homebuilder China Evergrande Group and its subsidiaries, Hengda and Tianji. The downgrades to ‘C’, from ‘CC’, reflect that Evergrande is likely to have missed interest payment on its senior unsecured notes and entered the consequent 30-day grace period before non-payment constitutes an event of default, Fitch said. (Reporting by Kanishka Singh in Bengaluru; Editing by Himani Sarkar)