LONDON, Aug 2: World oil prices faced a rollercoaster ride this week, tumbling on US demand concerns before rocketing higher on resurgent fears about the Iranian nuclear energy crisis, traders said.

Some commodities fell in value as poor US economic growth data reignited concerns about slowing demand for raw materials from the world’s biggest economy.

OIL: Oil prices stormed higher Friday after Washington set the weekend as a deadline for key crude producer Iran to reply to an international offer of incentives for a freeze in its nuclear drive.

We expect a response this weekend, Gonzalo Gallegos, a State Department spokesman, told AFP without specifying Saturday or Sunday.

In reaction, New York crude leapt as high as $128.60 per barrel and London Brent oil soared as high as 127.94.

Iran is the world’s fourth-largest crude oil producer and tension over its nuclear program helped push crude prices to record highs above $147 a barrel on July 11.

The US and other major powers suspect Iran’s nuclear drive is aimed at making weapons, but Tehran insists its objective is energy production.

Iranian Foreign Minister Manouchehr Mottaki said Thursday that there was no deadline and that his country had already replied. The US State Department had been vague about the deadline but narrowed it down on Friday.

Oil prices had tumbled on Thursday and earlier Friday after weaker-than-expected US growth figures stoked fresh worries about the outlook for global energy demand.

The US Commerce Department reported the American economy grew an annualised 1.9 per cent in the second quarter, missing the 2.3 per cent growth expected by most forecasts.It also revised 2007 fourth-quarter growth to a 0.2 per cent contraction -- the first reversal for the US economy since the 2001 recession.

Oil prices began the week higher, rallying on Monday after militants attacked a Royal Dutch Shell pipeline in Nigeria, leading the Anglo-Dutch energy giant to reduce output.

The market reversed direction on Tuesday after a report that US gasoline consumption fell last week for the 14th week in a row, according to credit card firm Mastercard.

But prices rebounded by more than four dollars Wednesday on news of an unexpectedly sharp decline in US motor fuel stockpiles.

The US government’s Department of Energy said that gasoline or petrol inventories dropped by 3.5 million barrels in the week ending July 25, overturning market forecasts for a gain of 400,000 barrels.

The news came amid the so-called US driving season -- when many Americans hit the roads for their summer holidays pushing up demand for motor fuel.

By Friday, New York’s main oil futures contract, light sweet crude for September delivery rose sharply to $126.76 a barrel, from $124 a week earlier.

Brent North Sea crude for September climbed to $126.20 from $125.02.

PRECIOUS METALS: Precious metals prices were held back by the strengthening US currency, which weighs on demand for dollar-priced goods because they become more expensive for buyers holding weaker currencies.

Dollar strength and improved US equity sentiment triggered further bouts of speculative selling in commodities, said metals analyst James Moore at TheBullionDesk.

On the London Bullion Market, gold fell to $912.50 per ounce at Friday’s late fixing from $920.50 a week earlier.

Silver firmed to $17.59 per ounce from $17.55.

On the London Platinum and Palladium Market, platinum decreased to $1,675 per ounce at the late fixing on Friday from $1,726.

Palladium slipped to $367 per ounce from $383.

BASE METALS: Base metals prices were mixed in subdued trade.

Poor economic data reminded the market of the weak underlying demand side fundamentals that might be signalling the end of the commodity boom, said BaseMetals analyst William Adams.

Overall the metals seem relatively directionless, which given the summer slowdown is not too surprising, but choppy trading is likely to remain in force. By Friday, copper for delivery in three months eased to $7,924 per ton on the London Metal Exchange from $7,930 a week earlier.

Three-month aluminium dropped to $2,929 per ton from $2,957.

Three-month lead rose to $2,150 per ton from $2,123.

Three-month zinc edged up to $1,850 per ton from $1,825.

Three-month tin decreased to $21,525 per ton from $22,449.

Three-month nickel rose to $18,750 per ton from $18,299.

GRAINS AND SOYA: Grains and soya prices edged higher.

By Friday on the Chicago Board of Trade, maize for September delivery increased to $5.87 per bushel from $5.77 the previous week.

November-dated soyabean meal -- used in animal feed -- firmed to $13.98 from $13.86.

Wheat for August delivery was up at $8.00 per bushel from $7.95.

COFFEE: Coffee prices rose.

By Friday on LIFFE, Robusta for September delivery leapt to $2,417 per ton from $2,330 a week earlier.

On the NYBOT, Arabica for September delivery rallied to 138.85 US cents per pound from 135.90 cents.

COCOA: Cocoa prices increased in London and New York.

By Friday on LIFFE, London’s futures exchange, the price of cocoa for September delivery rose to 1,592 pounds per ton from 1,482 pounds a week earlier.

On the New York Board of Trade (NYBOT), the September cocoa contract gained to $2,965 ton from $2,762.

SUGAR: Sugar prices gained ground.

By Friday on LIFFE, the price per ton of white sugar for October delivery jumped to 398 pounds from 355.90 pounds the previous week.

On NYBOT, the price of unrefined sugar for October delivery rose to 14.11 US cents per pound from 12.30 cents.

RUBBER: Malaysian rubber prices fell further.

On Friday, the Malaysian Rubber Board’s benchmark SMR20 fell to 309.60 US cents per kilogramme from 311.40 US cents a week ago.—AFP