TORONTO (Reuters) - The Toronto Stock Exchange's main index slipped nearly 250 points yesterday, stung by lower commodities, disappointing results from Telus Corp. and lingering worries over global mortgage and credit markets.

The S&P/TSX composite index closed down 248.38 points, or 1.8 percent, at 13,565.24 following a late-day plunge.

After a week of low volumes and changes in direction almost daily, the index hovers near its June lows. It gave up 1.3 percent in the week and swung in a wide range of more than 500 points.

The influential financial sector, which represents about a third of the overall index, has closed lower in seven of the last 10 trading days and this week dipped to its lowest level in the year.

Of the TSX's 10 main sectors, financials have been hardest hit by global subprime mortgage and credit worries, and slid another 1.8 percent yesterday.

Manulife Financial fell 90 Canadian cents, or 2.3 percent, to C$38.66, while Royal Bank of Canada sank C$1.35, or 2.5 percent, to C$53.50.

All sectors were lower, led by energy, materials, industrials and telecoms, which was dragged down by Telus, which fell C$2.90, or 4.8 percent, at C$57.50.

Telus said its quarterly profit sank 29 percent, which was below expectations for Canada's number two telephone company.

Commodity prices fell across the board, including oil, natural gas, nickel and copper.

Among oil and gas producers, Petro-Canada retreated C$2.53, or 4.4 percent, to C$54.68 while Canadian Natural Resources gave up C$2.16, or nearly three percent, to close at C$70.84.

World No. 2 zinc producer Teck Cominco Ltd. was down C$1.80, or 3.9 percent, at C$44.51.