COMMODITIES-Many gain on Fed's wider stimulus, wheat slumps

* Fed plans for stimulus helps boost oil more than 1 pct

* Gold, copper also up on Fed's ultra-low rates pledge

* Cocoa outperforms, up 3 pct, on speculative year-end buy

* Wheat at 5-mth low, dragged by USDA's Tuesday crop report

NEW YORK, Dec 12 (Reuters) - Oil, gold and copper closed up on Wednesday after the Federal Reserve's plans for more monetary stimulus weakened the dollar, boosting commodities that are priced in the currency. Agricultural markets fell broadly. Wheat slid for a fourth straight session and set a five-month low, extending Tuesday's loss of more than 3 percent due to a U.S. government report which forecast hefty future supplies. Cocoa was one crop that bucked the trend, rising 3 percent and even outperforming oil, as speculators built up a large net-long position before year-end in both the London and New York markets. Orange juice also gained, extending its three-month highs from the last session. The Thomson Reuters-Jefferies CRB index, which tracks 19 commodity markets, rose 0.5 percent after the gains in cocoa and oil were subdued by the broad losses in agriculture and natural gas, among others. Arabica coffee and raw sugar took the biggest hits, falling 2 percent each to two-year lows.

OIL RISES ON FED STIMULUS Crude oil rose on the Fed's extended stimulus plan and other factors such as a refinery fire in Texas and continued turmoil in the Middle East, the region that supplies most of the world's oil. The Fed committed to monthly purchases of $45 billion in Treasuries on top of the $40 billion per month in mortgage-backed bonds it started buying in September. The euro rose about half a percent against the dollar after the Fed's announcement, which encouraged buying of dollar-denominated commodities by those holding the single European currency.

In Port Arthur, Texas, Motiva's refinery, the largest in the United States, aborted a restart of its 350,000 barrel-per-day (bpd) crude unit after a fractured pipe caused a fire overnight.

In Syria, President Bashar al-Assad's forces were reported to have fired Scud-style ballistic missiles against rebels in recent days, escalating the 20-month civil war. Further support for oil came from the International Energy Agency, which substantially revised higher its estimate of global oil demand for the last three months of this year, and also said consumption would be stronger than previously forecast in 2013. "We were expecting the IEA to revise demand lower for next year in this morning's report, so the fact that they didn't was taken as a bullish signal," said Andy Lebow, vice president at Jefferies Bache in New York. But he cautioned that overall demand for OPEC's crude would still be lower in 2013 than 2012. Benchmark Brent crude oil in London finished up 1.4 percent at $109.50 a barrel. In New York, U.S. crude settled up 1.2 percent at $86.77.

GOLD JUMPS ON FED PLEDGE Gold prices jumped after the Fed said it will likely keep official interest rates near zero for as long as unemployment remains above 6.5 percent, inflation is no more than 2.5 percent for the next one to two years, and inflation expectations remain contained. "That's a bullish for gold for the Fed to say it will keep interest rates low until unemployment rate drops to 6.5 percent - it doesn't look that's going to happen anytime soon," said Bill O'Neill, partner of New Jersey-based commodities investment firm LOGIC Advisors. The spot price of bullion was up 0.6 percent at $1,720.20 an ounce by 1:02 p.m. (1802 GMT) U.S. gold futures for February delivery settled up half a percent at $1,717.90 an ounce. In copper, the benchmark three-month futures contract in London rose 0.3 percent to $8,130 per tonne. Copper futures in New York for March delivery settled up 0.8 percent at $3.7160 a lb.

GRAINS PRESSED BY USDA OUTLOOK Grains markets continued to suffer a day after the U.S. Department of Agriculture raised its estimate of U.S. 2012/2013 wheat ending stocks due to the slow pace of exports. It also increased its estimate of global inventories. Wheat for March delivery in Chicago settled down 1.2 percent at $8.12 per bushel. "Wheat is just trying to price itself as a feed grain. If you can't export it, it's going to price itself into feed," said Dan Cekander, analyst with Newedge USA in Chicago. Wheat competes in the feed market with corn. Corn fell to a three-week low, with the March contract finishing down 0.3 percent at $7.25-1/2 a bushel after touching $7.19.

Prices at 4:29 p.m. EST (2129 GMT)

LAST/ NET PCT YTD CLOSE CHG CHG CHG US crude 86.77 0.98 1.1% -12.2% Brent crude 109.58 1.57 1.5% 2.0% Natural gas 3.382 -0.030 -0.9% 13.1%US gold 1716.60 8.40 0.5% 9.6% Gold 1711.75 1.69 0.1% 9.4% US Copper 370.00 2.90 0.8% 7.7% LME Copper 8130.00 30.00 0.4% 7.0% Dollar 79.857 -0.204 -0.3% -0.4%US corn 721.00 -3.25 -0.5% 11.5% US soybeans 1473.50 1.50 0.1% 22.9% US wheat 794.75 -11.00 -1.4% 21.8%US Coffee 138.15 -3.00 -2.1% -39.5% US Cocoa 2490.00 56.00 2.3% 18.1% US Sugar 18.54 -0.34 -1.8% -20.2%US silver 33.707 0.766 2.3% 20.7% US platinum 1644.90 6.40 0.4% 17.1% US palladium 699.65 4.35 0.6% 6.6%