TORONTO (Reuters) - Canada’s main stock index fell on Monday, with energy shares down 2.5 percent after oil prices hit 2003 lows and worries about broader economic weakness weighing on consumer stocks.

A man walks past an old Toronto Stock Exchange (TSX) sign in Toronto, June 23, 2014. REUTERS/Mark Blinch

Canadian Oil Sands Ltd COS.TO popped 10 percent higher to C$8.27 after succumbing to Suncor Energy Inc's SU.TO sweetened offer, while almost every other energy stock fell.

Suncor declined 4.6 percent to C$29.77 and Canadian Natural Resources Ltd CNQ.TO lost 2.1 percent to C$23.92.

Oil prices slumped below $28 per barrel as traders braced for a rise in Iranian exports after sanctions against Tehran were lifted over the weekend. [O/R]

“If you had a solid, sharp bounce back above $30 that might have done something for sentiment, but as it stands it’s really hard for the index to get much traction,” said Elvis Picardo, strategist at Global Securities in Vancouver.

U.S. markets were closed for the Martin Luther King Jr. holiday, while an attempted rebound in European stocks fizzled.

The Toronto Stock Exchange's S&P/TSX composite index .GSPTSE ended the session down 131.29 points, or 1.09 percent, at 11,942.17.

“Negative sentiment is so overwhelming, it’s not really surprising to see the TSX trade down on a day like this,” Picardo said.

Even Prime Minister Justin Trudeau struck a more downbeat note, saying the weak Canadian dollar and low oil prices hurt large parts of the economy.

All ten main sectors fell, with consumer staples down 2.3 percent and consumer discretionary off 1.2 percent. The heavyweight financial sector slipped 0.5 percent.

Picardo said the market was bracing for China to report its slowest growth in 25 years on Tuesday.

“This is historically the worst ever start for markets, you’ve got major indices down 8 or 9 percent,” he said. “For the TSX to recover in the midst of that carnage is going to be very difficult.”

Beyond the oil patch, other major weights included convenience store operator Alimentation Couche-Tard ATDb.TO, down 2.9 percent at C$57.98, and telecom and media company BCE Inc BCE.TO, which lost 1.3 percent to C$54.09.

The materials group, which includes precious and base metals miners and fertilizer companies, lost 1.2 percent. Potash Corp POT.TO fell 2.8 percent to C$23.03.

Decliners outnumbered advancers by almost 6-to-1, with 36 stocks hitting fresh 52-week lows.