Rome, November 21 - Italian banks continued to weaken in September, writing down billions of euros in loans, according to the latest report released Wednesday by the Italian Banking Association (ABI). In September, non-performing loans in Italian banks totaled approximately 117.6 billion euros - 1.8 billion euros more than was reported the previous month, and 15.6 billion euros more than in September 2011. That marked an 15.3% increase this September compared with one year earlier. Net write-downs of loans at the end of September reached 67.2 billion euros, about 1.5 billion euros more than in August, and almost 12 billion euros more than was reported in September 2011. On a year-over-year basis, that meant an increase of 21.6%.