Sept 21 (Reuters) - Canada's main stock index fell on Monday as an increase in COVID-19 cases raised fears of a second round of lockdowns, while oil prices fell on the possible return of Libyan oil production.

* At 9:33 a.m. ET (1333 GMT), the Toronto Stock Exchange's S&P/TSX composite index was down 249.52 points, or 1.54%, at 15,949.45. (Reporting by Shashank Nayar in Bengaluru; Editing by Maju Samuel)