* Forecast for increases in supplies weigh on U.S. crude
* Upbeat U.S. economic data pressures gold
* Disappointing exports pull wheat to a 6-week low.
NEW YORK, Nov 5 (Reuters) - Oil and precious metals fell on Thursday, with gold falling for the seventh straight session, as upbeat U.S. economic data challenged assumptions of a prolonged Federal Reserve stimulus.
Speculation that the European Central Bank may announce lower interest rates this week pressured the Euro, while the dollar strengthened on data showing an acceleration in U.S. service sector activity.
Investors await U.S. October non-farm payroll data, due Friday, to forecast how long the Fed will maintain its stimulus policy. The Fed has stipulated that it will hold down interest rates until unemployment drops to 6.5 percent from its current 7.2 percent.
Expectations of a bumper harvest pressured corn to a near three-year low, while weak exports pushed wheat futures their lowest since Sept. 24.
In base metals, copper gained support from upbeat global manufacturing data, while aluminum closed down, but up from the day's low, which was the lowest since October.
The Thomson Reuters/Core Commodity CRB index, fell 0.26 percent to a near 1-1/2 year low, weighed by losses in 15 of the 19 commodities it tracks.
U.S. stocks seesawed throughout the day, as investors pondered the implications of the upbeat economic data on the Fed's stimulus.
"We've seen some quite good economic data out of the U.S., which has led to a rise in the dollar and has weighed on commodity prices, gold especially," Commerzbank analyst Daniel Briesemann said.
OIL SLIPS ON SUPPLIES
U.S. crude oil futures settled at a five-month low on Tuesday, pressured by forecasts for rising supplies and continued weak demand as Gulf Coast refineries were expected to remain offline at least through the end of this week.
A steady build in U.S. oil stocks has kept prices under pressure in recent weeks. Data is expected to show a new weekly increase of around 1.8 million barrels, according to a Reuters poll ahead of reports from industry group the American Petroleum Institute (API) and the Energy Information Administration (EIA).
"North America is creating an avalanche of oil that doesn't seem to have a home right now," said Gene McGillian, an analyst at Tradition Energy in Stamford, Illinois.
UPBEAT DATA WEIGHS ON PRECIOUS METALS
Gold prices fell on Tuesday after a reading of U.S. service-sector business activity came in stronger than expected. The business activity lifted the dollar, while the euro retreated ahead of a European Central Bank meeting later this week.
Speculation that U.S. monetary easing is set to end has pushed gold prices down 20 percent this year.
Gold demand in major consumer India failed to pick up after a soft week. Consumers bought little gold during Diwali, the Hindu festival of lights, over the weekend, although it is usually a popular occasion for bullion purchases.
GRAINS DOWN ON HARVEST PRESSURE
U.S. wheat futures fell to their lowest in nearly six weeks on Tuesday due to improving crop prospects in the U.S. Plains and declining demand in the export market, traders said.
Soybeans also fell, hitting their lowest since February 2012, while corn was close to unchanged and hovering near a three-year low. Expectations that an upcoming U.S. government report will show huge U.S. production of both crops weighed on both commodities.
Trading volume was thin across the agriculture markets as many traders were awaiting the U.S. Agriculture Department's monthly supply and demand reports, due on Friday.
"The grains are just biding time at this point," Matt Zeller, director of marketing information at INTL FCStone, said in a note to clients.