* TSX down 22.14 points, or 0.16 pct, at 13,524.82
* Six of 10 main sectors higher
* Oil, base metals, gold rebound (Updates to close, adds details, quotes)
By Claire Sibonney
TORONTO, March 16 (Reuters) - Toronto's main stock index reversed a near 1 percent gain in volatile trading on Wednesday, declining for a third straight session as Japan's nuclear crisis and clashes in the Middle East weighed on investor sentiment, despite higher commodity prices.
Materials slumped 0.5 percent after an early rally on rebounding prices for copper and gold. Teck Resources TCKb.TO slipped 1.2 percent to C$51.10 and Barrick Gold Corp (ABX.TO) fell 1.1 percent to C$47.02. [MET/L] [GOL/]
"The market hates, hates, hates uncertainty and we have nothing but, right now," said Rick Hutcheon, president and chief operating officer at RKH Investments.
"You've got the magnitude of the Japanese problems still to be unveiled ... you've got the unrest in the Middle East, you've got the uncertainty about the strength in the U.S. economy ... I could go on."
The outcome of Japan's nuclear crisis remained uncertain on Wednesday after workers withdrew briefly from a stricken power plant because of surging radiation levels and a helicopter was unable to drop cooling water on the most troubled reactor. [ID:nL3EF450]
Shares of uranium producers turned lower after early gains were hit by China's plan to tighten safety approvals for new reactors and as Japan's catastrophe intensified. Cameco Corp (CCO.TO) tumbled more than 8 percent to C$29.43. [ID:nN16160109]
Despite worries about natural disasters, geopolitical tensions and economic growth, Hutcheon said Canada was still relatively insulated -- compared with a steeper selloff south of the border that saw the Dow sag more than 2 percent -- with strong resource prices cushioning the TSX's fall.
Energy stocks rose 0.5 percent as Brent crude oil futures settled nearly 2 percent higher as violence in Bahrain, Yemen and Syria renewed fears about oil supply in the region. [O/R]
The Toronto Stock Exchange's S&P/TSX composite index .GSPTSE closed down 22.14 points, or 0.16 percent, at 13,524.82. Earlier, it was up almost 1 percent.
Don Vialoux, research analyst at JovInvestment Management, said the January low just below 13,200 was still providing significant support for the index.
Six of the TSX's 10 main sectors were actually stronger, but the weighty financials retreated 0.4 percent.
"People initially overreacted to the amount of exposure that Manulife had in Japan. I think sober second thoughts are causing people to re-evaluate that," said Michael Sprung, president of Sprung & Co Investment.
Another negative for North American markets was data showing U.S. housing starts suffered their biggest drop in 27 years, said Kate Warne, Canadian market strategist at Edward Jones in St. Louis, Missouri. [ID:nN16105108]
"It's just fed on itself with people being nervous and feeling uncomfortable with the risk that they're taking on equities. They're selling and asking questions later," she said.
"In the very short term, it wouldn't surprise me if we continue to see markets decline until we get some resolution of what's going on with the nuclear reactors in Japan.
In individual company news, Research in Motion RIM.TO fell 1 percent to C$59.46 after an Indian minister said security agencies are not satisfied with a plan offering access to data on its BlackBerry Messenger services. [ID:nN16266498] (Reporting by Claire Sibonney; editing by Rob Wilson)