*TSX down 157.23 points, or 1.33 percent, at 11,681.06
*All TSX sectors lower (Adds details, quote)
By Jennifer Kwan
TORONTO, Aug 11 (Reuters) - Toronto's main stock index fell sharply on Wednesday morning as commodity prices sank on persisting worries about weaker growth in China and the United States.
The index's materials sector fell as copper prices tumbled to their lowest level in more than a week as confidence crumbled in the face of U.S. dollar strength and renewed worries about growth prospects in the United States. [MET/L] Teck Resources TCKb.TO dropped 2.4 percent to C$35.21.
The TSX followed Wall Street lower as the U.S. Federal Reserve's gloomier assessment of the economy rattled investors and the U.S. central bank's measures to support it failed to reassure world markets. [.N] [ID:nN09275781]
"People are digesting (the Fed) comments and they haven't encouraged people too much," said David Cockfield, senior vice president and portfolio manager at MacNicol and Associates Asset Management. "The realization is sinking in that it's going to be a long, hard grind ahead for the U.S. economy. Of course that feeds back into Canada as well."
At 9:58 a.m. (1358 GMT), the Toronto Stock Exchange's S&P/TSX composite index .GSPTSE was down 157.23 points, or 1.33 percent, at 11,681.06, with all of its 10 main groups lower.
Also darkening the mood, China reported a slowdown in factory output, adding to a picture of softening domestic demand painted by data on Tuesday that showed a sharp drop in import growth. [ID:nTOE67A01A]
In individual company news, Research In Motion RIM.TO was up 0.3 percent at C$57.97 after reports that it had reached a deal to keep its service going in Saudi Arabia. However, sources said India may temporarily shut down BlackBerry services if security concerns are not addressed in a meeting on Thursday. [ID:nSGE67A09E]
Metro Inc's MRUa.TO quarterly earnings climbed 6.6 percent, helped by improved operations and higher revenue, even though same-store sales slipped and food price deflation persisted. Metro shares fell 0.6 percent C$43.56. [ID:nN11201236]
$1=$1.04 Canadian Reporting by Jennifer Kwan; editing by Peter Galloway