Bulgaria's M3, the broadest gauge of money supply, increased 9.2% year-on-year to 91.6 billion levs ($53.7 billion/46.8 billion euro) at the end of September, compared to an annual growth of 9.5% at the end of August, the central bank, BNB, said on Tuesday. The narrowest measure of money supply, M1, rose 13.5% on the year to 51.9 billion levs at the end of September, compared to a 14% annual rise at the end of August, BNB said in a statement.Net foreign assets increased 6.5% year-on-year at end-September, reaching 55.6 billion levs, while net domestic assets added 7.8% to 55.2 billion levs.