Wheat futures rallied on Monday after data suggesting a spike in demand for U.S. supplies of the grain, and gold prices firmed on bets that new Federal Reserve Chair Janet Yellen will not accelerate the winding down of the U.S. monetary stimulus.

Brent crude oil fell by nearly $1 per barrel, pressured by sinking heating oil prices, as the market looked toward the end of a long and frigid winter and as supplies increased from Libya and the North Sea.

Natural gas futures tumbled to its lowest in more than two weeks, also on forecasts for warmer weather in the longer-term.

In base metals, copper and aluminium finished lower. In crop markets outside of wheat, sugar, soybeans, cocoa and lean hogs all ended down. 

The broad lower close weighed on the Thomson Reuters/Core Commodity Index, a global benchmark for commodities. The index settled down 0.3 percent after 10 of its 19 components ended in the negative.

Wheat futures surged after the U.S. Department of Agriculture announced a bigger-than-expected cut in ending-stocks of the grain in data issued Monday.

Traders said there had been a noticeable pick up in demand for U.S.-grown wheat since prices hit a 3-1/2-year low late last month. 

The USDA dropped its U.S. ending-stocks figure to 558 million bushels, 50 million below its January estimate and lower than trade expectations for 603 million bushels. The cut was entirely due to a 50 million-bushel boost to its export forecast.

"The balance table on the wheat market is probably the tightest now," said Don Roose, analyst with U.S. Commodities in West Des Moines, Iowa.

At the close of Monday's session, soft red winter wheat settled up 7-1/4 cents, or up 1.3 percent, at $5.84-3/4 a bushel on the Chicago Board of Trade. Hard red winter wheat in Kansas City and spring wheat in Minneapolis, both high-protein material prized on the export market, jumped about 2 percent each.

Gold prices rose on expectations that Fed Chair Yellen will not fast-track the winding down of the U.S. monetary stimulus, which had been a boon to prices of the precious metal.

Yellen is due to make her first testimony to the U.S. Congress on Tuesday, and financial markets are hoping for reassurance that the Fed's bond purchases will continue.

The spot price of gold was up 0.6 percent at $1,274.29 an ounce by 4:45 p.m. EST (2145 GMT), extending last week's rise of nearly 2 percent.

(By Barani Krishnan; Editing by David Gregorio) Word Count: 518