TORONTO (Reuters) - Toronto's main stock index ended lower yesterday, weighed down by disappointing results and forecasts from market heavyweight Potash Corp.

The world's largest fertiliser producer led the index's decline all session, ending down 4.55 percent after C$111.26, after it reported earnings and a profit outlook well below market expectations.

Potash shares fell as much as eight percent during the day, and despite the company's optimism that fertilizer demand would improve this year, it triggered a sell-off in other fertiliser stocks.

Also dragging the index down was Canada's largest oil and gas company, Suncor Energy, off 1.04 percent at C$34.35, as the price of oil was fairly flat near $74 a barrel.

The Toronto Stock Exchange's S&P/TSX composite index ended down 69.91 points, or 0.62 percent, at 11,274.2, though it managed to pare some losses after hitting its lowest level in more than two months earlier in the day.

Nine of the index's 10 main groups declined.

"Very rarely does it go one direction solidly, but we're still seeing some weakness. There's uncertainty," said Steve Ibel, institutional equities trader at Beacon Securities in Halifax, Nova Scotia.

"People are just reluctant to take on large positions. Right now, they're playing out month-end."

Soft quarterly results from big US companies, ongoing concern about the uneven US economic recovery, and fiscal worries in Greece have all contributed to negative investor sentiment.

The Canadian dollar limped to a lower close against the US dollar yesterday, pressured by a drop in risk appetite that manifested itself in a stronger greenback and sliding equity markets.

Concern about the fiscal health of Greece and other smaller euro zone countries helped lift the US dollar to a six-and-a-half month peak against the euro.