Undated (AP) _ Exports demand pushed down grain futures prices Wednesday on the Chicago Board of Trade while crude oil futures rose amid OPEC-member opposition to an accord increasing the cartel's production ceiling.

On other markets, wheat prices were mixed, corn drifted lower, livestock and pork fell and precious metals declined.

''There's been very strong export demand for wheat,'' said Jerry Zusel, manager of CBOT floor operations for Balfour Maclaine Corp.

Zusel said Egypt late Tuesday tendered for 500,000 metric tons of wheat and the Agriculture Department on Wednesday morning targesed Egypt for 1 million metric tons of export bonus wheat.

Soybean prices were depressed by a forecast of good harvest weather with no frost threatened and better than expected early harvest yields, said Victor Lespinasse, a trader in Chicago for Dean Witter Reynolds Inc.

The soybean contract for November reached a seven-week low of $5.64 during the day.

Wheat prices were mixed, weakened by a lack of commercial buying while supported by strong export demands, traders said. Corn slipped lower from lack of any major demand.

Wheat settled 3 3/4 cents lower to 4 1/4 cents higher, with December at $3.98 1/2 a bushel; corn was 3/4 cent to 1 3/4 cents lower, with December at $2.28 3/4 a bushel; oats were 1/2 cent to 1 cent higher, with December at $1.44 1/2 a bushel; and soybeans were 1/4 cent to 1 1/2 cents lower, with November at $5.65 1/4 .

Crude oil futures prices moved higher when news reached the New York Mercantile Exchange of OPEC member opposition to an Iranian proposal to increase the oil cartel's production ceiling for the rest of the year.

Meeting in Geneva, OPEC ministers struck a deal to boost their production ceiling a modest amount in the final months of the year to 20.5 million barrels. But Algeria and Kuwait indicated they would not go along.

Heating oil prices were up, as support came from Tuesday's American Petroleum Institute inventory report, said Jim Ritterbusch, vice president of trading and research for Carson Petroleum Co. in Chicago.

Unleaded gasoline futures were mostly lower.

Crude oil settled 6 cents to 24 cents higher, with November at $19.59 a barrel; heating oil was .70 cent to .90 cent higher, with October at 58.46 cents a gallon; and unleaded gasoline was 1.64 cents lower to .27 cent higher, with October at 58.74 a gallon.

On the Chicago Mercantile Exchange, futures prices for livestock and pork were mostly lower.

Prices for live hogs and frozen pork bellies moved lower as traders, awaiting Friday's hog inventory report from the Agriculture Department, were concerned over some weakness in the cash markets, said Paul Hare, an analyst in Chicago with Linnco Futures Inc.

Sizeable deliveries of cattle to farmer markets weighed on cattle futures, he said.

Live cattle settled .23 cent lower to .25 cent higher, with the contract for October at 72.10 cents a pound; feeder cattle were .05 cent to .32 cent lower, with September at 83.10 cents a pound; live hogs were .15 cent higher to .25 cent lower, with October at 43.20 cents a pound; and frozen pork bellies were unchanged to .38 cent lower, with February at 48.27 cents a pound.

Futures prices for precious metals were lower on the Commodity Exchange in New York.

''Several central banks took dollar down again, but gold was not able to rally,'' said Jim Steel, metals analyst in New York from Refco Inc.

''The traditional relationship between the dollar and gold is not there right now, because of the presence of longtime fundamentals - inflation is low and interest rates are coming down. Neither make gold very attractive,'' he said.

Silver has been suffering from overproduction, he said.

Gold settled 50 cents to $1 lower, with the contract for delivery in September at $367.60 a troy ounce; and silver was 1.8 cents to 2.2 cents lower, with September at $5.245 a troy ounce.