TORONTO (Reuters) - Toronto's main stock index fell hard yesterday as resource prices came under pressure on news that China's central bank was tightening monetary policy at a faster than expected pace.

In its strongest step yet, China rocked global financial markets with a surprise increase in banks' required reserves, a move that pushed gold to a session low, and knocked down commodity currencies, including the Canadian dollar, against the greenback.

The Toronto Stock Exchange's S&P/TSX composite index ended down 126.95 points, or 1.06 percent, at 11,820.18. All the gains made in the first sessions of the new year were within about 20 points of being wiped out at one point in the day. The index ended 2009 at 11,746.11.

Energy shares fell as the price of oil headed down towards $80 a barrel, while mining shares sagged on a weakening price for bullion. Suncor Energy was down 1.8 percent at C$37.87. Gold mining companies such as Barrick Gold , off 2.5 percent at $41.92, also weighed.

"Today's trading action does stand out a little bit because it's the first significant down day we've had in a little while," said Elvis Picardo, analyst and strategist at Global Securities in Vancouver.

"But I do think the markets are going to be in this manic-depressive phase for the next couple of weeks at least because the earnings reports are going to drive a lot of the action."

The decline on Toronto's main equities index was exacerbated by a disappointing start to the earnings season in the US as Alcoa Inc.'s quarterly results stoked unease about the economic recovery. The bulk of corporate Canada's results get will start coming out near the end of the month and into February.

Canadian fertiliser makers were hit hard after the US raised its estimate for 2009 corn production to a record high, sending grain futures crashing.

Potash Corp. of Saskatchewan, down 3.66 percent at C$122.30, was the biggest single drag on the market, while Agrium Inc. was down 3.3 percent at C$69.15.