Aug 31 (Reuters) - Canada's main stock index opened lower on Friday as Canadian officials expressed concern that a final NAFTA deal might not be concluded on Friday, according to a report.
* At 9:31 a.m. ET (13:31 GMT), the Toronto Stock Exchange's S&P/TSX composite index .GSPTSE was down 17.58 points, or 0.11 percent, at 16,353.97.