CANADA STOCKS-TSX dives 3.8 percent as economic worries weigh

* Energy, financials lead TSX retreat

* Materials only advancer as gold issues shine

* Suncor biggest decliner, reports rare loss (Adds details, analyst comments)

By Natalie Armstrong

TORONTO, Jan 20 (Reuters) - Toronto's main stock index fell 3.8 percent on Tuesday as a relentlessly gloomy global economic outlook spurred a broad-based selloff led by energy and financial issues.

While oil prices jumped 6 percent ahead of the expiration of the February U.S. futures contract, energy shares led the TSX retreat, slumping 6.8 percent.

Shares of Suncor Energy (SU.TO), the day's biggest decliner, slumped 15.84 percent to end at C$22.10 after Canada's second-biggest oil sands producer reported a quarterly loss, slashed capital spending and halted a C$20.6 billion oil sands expansion. [ID:nBNG347039]

Suncor is the latest oil sands producer to cut expansion plans and many analysts say new projects need crude prices to be much higher than the current level of around $39 a barrel. [ID:nN20422515]

"Most of those oil sands projects are either canceled or put on hold," said Sal Masionis, stockbroker at Brant Securities.

"That means in the future we'll have shortages of oil and the oil prices will go up."

EnCana (ECA.TO) shares ended 5.5 percent lower, at C$52.67.

The Toronto Stock Exchange's S&P/TSX composite index .GSPTSE closed down 336.55 points, or 3.81 percent, at 8,504.93. All but one of its 10 main sectors ended lower.

The TSX opened slightly higher after the Bank of Canada cut its overnight rate by 50 basis points to 1 percent [ID:nN20403457]. But the market quickly turned negative and stayed in the red all day.

Financial issues sank 5.8 percent over a lack of confidence in the global banking sector after Royal Bank of Scotland (RBS.L) announced the biggest loss in British corporate history on Monday.

"All of our banks are down big time, basically the same situation as in the U.S., basically the same situation in the U.K.," said Fred Ketchen, director of equity trading at ScotiaMcLeod.

"That whole financial services sector is weeping badly and it looks as though it's going to continue a little while longer."