In other commodity trading, grain and cotton prices closed mostly lower ahead of a key set of government crop estimates for the United States.At the New York Mercantile Exchange, oil markets continued to rise on the shock effect of unexpected declines in US crude oil stocks the last two weeks. Crude oil stockpiles are at a 24-year low, according to the American Petroleum Institute (API), an industry group.

Crude oil closed 99 cents higher at $31.34 a barrel, up more than 7 percent in the last two days.

The rise followed Tuesday night's weekly report from API on US petroleum usage. API reported that for the week ended on August 4, crude oil stocks fell 2.1 million barrels. Traders had expected a rise of 2 million. That came one week after API reported stocks down 9 million barrels, when traders had expected a 1 million barrel rise. Crude stocks in the US are now the smallest since March 1976.

In addition, this week the industry group also said that stocks of distillates, including diesel and heating oil, had also fallen - down 1.2 million barrels when traders had expected a rise of 1.7 million as part of the usual seasonal buildup of heating oil supplies ahead of the US winter.

Talk of mechanical problems at some US refineries also fed concerns about product supplies. In addition, major oil firms said on Thursday that OPEC kingpin Saudi Arabia, recently an aggressive shipper of oil, had trimmed the amount of oil available for September loadings, traders said.

Buoyed by these worries, refined product prices soared. Heating oil for September delivery closed 2.74 cents higher at 86.28 cents a gallon and September gasoline jumped 4.44 cents at 92.64 cents.

Elsewhere, grain markets traded ahead of the US Department of Agriculture's monthly crop estimates due out on Friday morning. Weekly export sales reported by USDA were strong for last week, but a record corn and soybean crop is expected to be projected in Friday's report.

At the Chicago Board of Trade, soybeans for September delivery closed 4-1/2 cents a bushel higher at $4.47-1/2. September corn closed 1 cent lower at $1.77-1/4 but September wheat rose 1/4 cent at $2.35-3/4. All the grains continue to hover near life-of-contract lows due to swollen US stocks and excellent summer weather in the US corn belt, which has erased fears of drought damage. Export demand is booming, but it needs to stay that way for many months, traders said.

In a weekly report on Thursday, the USDA said export sales of soybeans last week rose to 1,069,300 metric tons, above the highest trade estimate of 800,000 tons. Corn sales were strong at 1,267,300 tonnes, above the top trade estimate of 1,100,000 tonnes. Wheat sales followed the same pattern at 1,098,900 tonnes, well above a range of estimates for 450,000 to 750,000 tonnes. Cotton prices also closed lower ahead of the crop estimates, with December cotton at the New York Board of Trade ending 1.58 cents lower at 62.77 cents a pound. "Some of the weakness may be tied to the fact that prices may have become overbought the last couple of days," said Alan Feild of STA Trading Services in Memphis.

Cotton analysts put their average guess at the size of this year's cotton crop at 19.27 million 480-pound bales, up from 16.97 million produced last year.

As with grains, cotton exports have been strong this year with the depressed US prices. For the cotton marketing year that ended on July 31, USDA said on Thursday that US cotton export sales totalled 6.13 million bales - up 61 percent from the 3.81 million bales shipped in the prior season.