Gold and silver futures staged a late rally Thursday, reacting to weakness of the dollar and a threat that Israel's invasion of Lebanon could force Arab countries to use oil as a political weapon.

The threat came from Palestinian Liberation Organization spokesman Ghasi Hussain, who was quoted as saying at a Vienna news conference that hostilities in the Middle East would cause Arab nations to "use oild and capital as political weapons."

Gold futures traded on the Comex in New York shot up about $2 an ounce to $185.20 in the March contract, while silver deliveries averaged gains of 7.7 cents an ounce. Platinum closed ahead $2.20 an ounce in all months.

he upswing in silver futures also influenced a turnaround at the Chicago Board or Trade, where nearby soybean contracts spurted almost 7 cents higher in the final moments.

At the close of grain trading, soybeans were 2 1/2 to 7 cents higher, with March contracts quoted at $6.74 a bushel; wheat was 3/4 cent lower to 1/2 cent higher, March $2.80 1/4; corn was 1/4 cent lower to 2 cents higher, March $2.41 3/4 and oats were 1/2 cent lower to 1/2 cent higher, March $1.32.

Live cattle futures, which surged to a four-year high during the preceding session, staggered 0.9 to 1.5 cents a pound on the chicago Mercantile Exchange.

Coffee futures traded in New York also slumped as much as 4 cents a poknd, the daily limit. Coffee roasters exhibited little interest in buying at current prices, traders said.

"There was little fresh news, but the market acted erratically as people tried to weigh the export embargo by Central American nations against indications that Brazil and Colombia are eager to sell their coffee," said a coffee analyst.