(Updates throughout with new details, commentary, market reaction)
* TSX down 16.78 points, or 0.11 percent, to 14,930.73
* Half of the TSX's 10 main groups decline
By Solarina Ho
TORONTO, June 25 (Reuters) - Canada's main stock index slipped on Thursday, after hitting a 2-1/2-week high this week, but declines were modest, with many investors awaiting some sort of news about and resolution to Greece's debt situation.
"Clearly the biggest concerns out there include Greece. It's very psychological at this point. It's testing Europe, testing central bankers. People don't know what the effects will be," said Irwin Michael, portfolio manager at ABC Funds.
Energy names were among the biggest drags on the index, offsetting gains elsewhere including in the hefty financial sector.
Suncor Energy Inc fell 1.7 percent to C$35.08, while Encana Corp declined 2.9 percent to C$14.31.
The overall group retreated 1.1 percent, hurt by oil prices that were pulled lower by Greece uncertainties and the potential easing of sanctions on crude-producing Iran.
U.S. crude prices were down 0.9 percent to $59.73 a barrel, while Brent crude lost 0.6 percent to $63.13.
At 11:06 a.m. EDT (1506 GMT), the Toronto Stock Exchange's S&P/TSX composite index fell 16.78 points, or 0.11 percent, to 14,930.73.
Of the index's 10 main groups, half were in negative territory.
The materials group, home to mining companies, was also down, giving up 0.7 percent, with First Quantum Minerals Ltd falling 4.2 percent to C$17.37. Teck Resources Ltd lost 3.02 percent to $13.50.
Financial names, which include banks and insurers, offset some of the resource losses with a 0.5 percent gain. About seven of the TSX's 10 stocks carrying the most weigh on the positive side were from that group. Bank of Montreal climbed about 1.0 percent C$75.89.
Declining issues outnumbered advancing ones on the TSX by 138 to 102, for a 1.35-to-1 ratio on the downside.
The index was posting 5 new 52-week highs and 2 new lows.
Reporting by Solarina Ho; Editing by Meredith Mazzilli