TORONTO (Reuters) - Canada's main stock index plunged on Monday, with drugmaker Valeant Pharmaceutical International (>> Valeant Pharmaceuticals Intl Inc) stunned by U.S. congressional rebuke and global malaise hurting a range of Canadian resource companies as commodities prices fell.

Shares of Valeant, a major weight on the index, fell 16.3 percent to C$221.81 after Democratic lawmakers attacked "massive" price increases for two heart drugs after the company bought them in February.

While Valeant's fall was by far the biggest reason for the day's decline, a range of financial and resource-related stocks - the index's biggest groups - also fell amid unease over the economic health of China and other big emerging markets.

"People are still blaming global growth, China. But I think it's now beyond that," said Allan Small, a senior investment adviser at HollisWealth. "I think it's now just this overall feeling of negativity in these markets."

The Toronto Stock Exchange's S&P/TSX composite index <.GSPTSE> ended down 373.99 points, or 2.8 percent, at 13,004.58. All 10 main groups fell, with energy retreating 2.6 percent and the materials group down 4.6 percent.

U.S. crude prices were down 2.8 percent to $44.42 a barrel, while Brent crude lost 2.6 percent to $47.32.[O/R] Gold futures fell 1.2 percent to $1,133.2 an ounce [GOL/], and copper prices declined 1.2 percent to $4,965 a tonne. [MET/L]

Goldcorp Inc (>> Goldcorp Inc.) fell 6.6 percent to C$16.60 and Canadian Natural Resources Ltd (>> Canadian Natural Resources Limited) lost 2.8 percent to C$25.47.

Decliners outnumbered advancers by 227 to 13, and the index posted one new 52-week high and 25 new lows.

Royal Bank of Canada (>> Royal Bank of Canada) fell 1.2 percent to C$71.05 and Brookfield Asset Management (>> Brookfield Asset Management Inc) slipped 2.9 percent to C$40.55, while the overall financial sector lost 1.3 percent.

Transcanada Corp (>> TransCanada Corporation) was another weighty loser, sliding 4.8 percent to C$41.55. The pipeline operator's planned Keystone KL pipeline has resurfaced as a U.S. election issue.

(Reporting by Solarina Ho; Editing by Andrew Hay and Tom Brown)

By Solarina Ho and Alastair Sharp