* TSX ends down 201.97, or 1.68 pct, at 11,813.00
* Nine of index's 10 main sectors lower
* Miners lead slide; oils retreat on weak crude (Updates to close, adds quotes)
By Jennifer Kwan
TORONTO, May 17 (Reuters) - Toronto's main stock index fell for a third straight session on Monday 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 6.3 percent to C$33.11 and First Quantum (FM.TO) sank 6.6 percent to C$64.98 as industrial metals plummeted. [MET/L]
"There's concern that the international economies, in particular China, are slowing down. People extrapolate that to make the assumption that you're going to see lower commodity prices," said Irwin Michael, portfolio manager at ABC Funds.
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]
Investor sentiment was also bruised by concern that efforts to tackle the euro zone debt crisis could stifle the global economic recovery. [MKTS/GLOB]
The two factors are intertwined, said Julie Brough, vice-president at Morgan Meighen & Associates.
"It affects China's and Asia's export markets if you have very slow economies in Europe and the U.S.," she said.
The Toronto Stock Exchange's S&P/TSX composite index .GSPTSE ended down 201.97 points, or 1.68 percent, at 11,813.00. It slumped as low as 11,695.61, its lowest level in a week. Nine of the index's 10 main groups were lower.
A tumble in oil prices hit TSX energy shares, with Suncor Energy down 2.5 percent to C$31.26, while Canadian Natural Resources (CNQ.TO) fell 1.7 percent to C$71.37. [O/R]
The materials group, home to mining and fertilizer companies, sank 2.8 percent while energy issues fell 2 percent.
The losses on the TSX were not limited to commodity-linked issues. Also weighing were financials, down 1.3 percent, and industrials, which sank 1.7 percent.
It was the third straight lower close for the Toronto index.
"People are edgy. You know the old saying, sell in May and go away? It's still May," said Michael.
"Clearly, it looks like it's a bit of a buyers' boycott. A lot of people are stepping away, not being sure what to do. When that happens it's a question of supply and demand," he said.
In individual company news, Toronto-Dominion Bank (TD.TO) sank 1.9 percent to C$71.98 after it said it would buy troubled U.S. lender South Financial Group Inc TSFG.O for $191.6 million to build on its presence in the U.S. Southeast, especially Florida. [ID:nSGE64G0HT]
The consumer staples group was the lone sector in the black, up 0.11 percent, with grocery chain Metro Inc MRUa.TO up 0.6 percent at C$44.45 and dairy company Saputo Inc (SAP.TO) up 0.4 percent at C$28.56.
The blue chip S&P/TSX 60 index .TSE60 closed 11.24 points lower, or 1.59 percent, at 695.48.
$1=$1.03 Canadian Reporting by Jennifer Kwan; editing by Rob Wilson