(Reuters) - Standard and Poor's Rating Services raised its long-term sovereign credit rating on Greece to 'CCC+' from 'CCC-', saying it believed default was no longer inevitable in the next six to 12 months. S&P said the outlook was stable, with the possibility of Greece leaving euro zone now less than 50 percent. (Reporting by Anjali Rao Koppala in Bengaluru; Editing by Ted Kerr)