* TSX down 313.39 points, or 2.6 percent, at 11,701.58
* Index down for 3rd straight session; touches 1-week low
* Miners lead TSX lower; oils retreat on weak crude (Adds details, quotes)
By Jennifer Kwan
TORONTO, May 17 (Reuters) - Toronto's main stock index skidded on Monday afternoon as oil and metal prices tumbled on concerns about euro zone debt and weaker growth in China, knocking commodity issues lower.
Teck Resources TCKb.TO fell 8.3 percent to C$32.40 and First Quantum (FM.TO) sank 6.8 percent to C$64.84 as industrial metals plummeted. [GOL/] [MET/L]
"It comes back to the same principals everybody's talking about: the fear that there's going to be reduced growth in the world and China's going to have to put the brakes on harder because their economy is potentially getting overheated in some sectors," said Julie Brough, vice-president at Morgan Meighen & Associates.
"If they slow down, the demand for base metals slows down."
Toronto's slide came as China's key stock index tumbled 5.07 percent on Monday to its lowest close in a year. That fall was led by property issues, as retail investors fled the market after a month-long rout sparked by a severe government clampdown on surging property prices. [.SSEC] [ID:nTOE64G065]
A tumble in oil prices below $70 a barrel hit TSX energy shares, with Suncor Energy down 3.5 percent to C$30.93, while Canadian Natural Resources (CNQ.TO) fell 3.1 percent to C$70.33. [O/R]
At 12:50 p.m. (1650 GMT), the Toronto Stock Exchange's S&P/TSX composite index .GSPTSE was down 313.39 points, or 2.6 percent, at 11,701.58. It slumped as low as 11,695.61, its lowest level in a week. All of the index's 10 main groups were lower.
The materials group, home to mining and fertilizer companies, sank 3.5 percent while energy issues slid 3.2 percent.
The losses on the TSX were not limited to commodity-linked shares. Also weighing heavily were financials, down 2.3 percent, and industrials, which sank 3 percent.
In individual company news, Toronto-Dominion Bank (TD.TO) sank 2.5 percent to C$71.55 after it said it would buy troubled U.S. lender South Financial Group Inc TSFG.O for about $191.6 million to build on its presence in the U.S. Southeast, especially Florida. [ID:nSGE64G0HT]
($1=$1.04 Canadian) (Reporting by Jennifer Kwan; editing by Rob Wilson)