* TSX down 57.82 points, or 0.47 percent, to 12,138.69
* Energy, mining shares lead TSX lower
* Suncor results help cushion index fall (Adds details, quote)
By Jennifer Kwan
TORONTO, May 4 (Reuters) - Toronto's main stock index fell on Tuesday morning as worries about Greece's aid package persisted, hitting oil and metals prices and sending energy and mining issues lower.
The index's energy sector dropped 0.7 percent. EnCana Corp ECA.TO was down 0.2 percent at C$33.42, while Canadian Natural Resources CNQ.TO sank 1.8 percent to C$77.49.
Miner Teck Resources TCKb.TO dropped 2.8 percent to C$37.70, while First Quantum Minerals FM.TO fell 4.3 percent to C$70.78, which weighed on the index's materials group.
"We are down on the Greek concerns. Commodities are super weak," said Francis Campeau, broker at MF Global Canada in Montreal.
At 9:58 a.m. (1358 GMT), the Toronto Stock Exchange's S&P/TSX composite index .GSPTSE was down 57.82 points, or 0.47 percent, at 12,138.69.
The Toronto index took its cue from overseas stock markets, which dropped as investors remained skeptical that a weekend agreement among European countries and the International Monetary Fund to bail Greece out of its debt problems would succeed. [MKTS/GLOB] [.N]
The euro retreated against the greenback on fears that Greece's woes would spread to other vulnerable euro zone countries. [FRX/]
That concern helped to push down the price of oil, which fell below $85 a barrel, while base metals were also knocked lower on worries China would step up its credit tightening campaign. [O/R] [MET/] [ID:nTOE64100Q]
Financials fell 0.6 percent with Canada's biggest lender, Royal Bank of Canada RY.TO, down 0.4 percent to C$62.15.
Although lower, the TSX index was a relative outperformer, Campeau said.
"The way it has to be seen is that the TSX is actually quite strong compared to the rest of the world. Europe equities are down heavily on the Greek concerns," he said.
He said solid earnings were helping to cushion the fall.
For instance, shares of Suncor Energy Inc SU.TO, Canada's top energy company, climbed 1.7 percent to C$35.28 after it reported quarterly profit that beat market expectations, helped by additional production from its acquisition of Petro-Canada and higher crude oil prices. [ID:nN03213638]
($1=$1.02 Canadian) (Reporting by Jennifer Kwan; editing by Peter Galloway)