(Updates throughout with fresh details, market comment, stock movements)
* TSX down 42.71 points, or 0.29 percent, to 14,713.34
* Nine of the TSX's 10 main groups were down
By Solarina Ho
TORONTO, June 16 (Reuters) - Canada's main stock index fell on Tuesday on persistent Greek debt worries and as investors awaited the Federal Reserve's looming interest rate decision.
The TSX, which has been grinding slowly lower since April, saw most sectors mired in the red, with consumer discretionary stocks the lone gainer.
Suncor Energy Inc was among the heftiest decliners on the index, falling 0.7 percent to C$34, along with Enbridge Inc, which declined 0.7 percent to C$55.44.
The overall energy sector retreated 0.3 percent despite modest gains in U.S. oil prices.
At 10:55 a.m. EDT (1455 GMT), the Toronto Stock Exchange's S&P/TSX composite index was off 42.71 points, or 0.29 percent, at 14,713.34.
Of the index's 10 main groups, only the consumer discretionary group managed to add 0.4 percent.
"A lot of people are waiting for (the Fed) - basically every syllable of their pronouncement and whatever their view is looking forward," said Irwin Michael, portfolio manager at ABC Funds.
"Most investors are also waiting to find out what happens with Greece," Michael added. "It overhangs. If that could be resolved one way or another, it takes a lot off the market here, because there's a lot of negativity out of Europe and elsewhere."
The materials group, home to mining stocks, saw some of the index's bigger losses, retreating 1.0 percent, with miners tracking softer metal prices. Barrick Gold Corp shares fell 2.3 percent to C$13.83.
Gold futures fell 0.7 percent to $1,177 an ounce.
Copper prices declined 0.9 percent to $5,765.5 a tonne.
Declining issues outnumbered advancing ones on the TSX by 144 to 85, for a 1.69-to-1 ratio on the downside. (Reporting by Solarina Ho; Editing by James Dalgleish)