Gold prices tumbled to a two-year low and crude oil slumped to a nine-month trough this week, as commodity markets were rocked by weaker-than-expected first-quarter economic growth in key consumer China.

Investors were spooked after China released data Monday showing growth in the world's number two economy had slowed to 7.7 percent in the first three months of 2013, below forecasts and indicating a recent pick-up remained fragile.

Many raw materials recovered ground later in the week, in line with global stock markets, as bargain-hunters moved in.

PRECIOUS METALS: Gold nosedived to $1,321.95 an ounce on Tuesday, hitting a level last seen at the start of 2011.

The metal had already sunk 10.9-percent on Monday -- its sharpest daily slump since 1983 -- owing to weak Chinese growth data and reports that Cyprus was planning to sell some of its gold reserves.

"It's the speed of it and the extent of the sell-off that shocked everybody," Kelly Teoh, a market strategist at traders IG Markets in Singapore, told AFP.

"Gold has had a 12-year run. It's done really well. But if you're holding a position and you're seeing you're getting a better yield in the cash markets it's a natural move," said Teoh.

Julian Jessop, chief global economist at research group Capital Economics, said that the slump appeared to have been triggered by speculators.

He added: "Gold has also been caught up in the broad-based weakness in commodity markets, including oil and industrial metals, due to softer US and Chinese data. Once trading calms down, we expect gold to stage at least a partial recovery."

Sister metal silver meanwhile recoiled on Tuesday to $22.07 an ounce -- hitting a low point last witnessed in October 2010. Platinum reached a 14-month low of $1,375.50 an ounce and palladium a near six-month trough at $647.25 an ounce.

By late Friday on the London Bullion Market, the price of gold tumbled to $1,405.50 an ounce from $1,535.50 a week earlier.

Silver slid to $23.66 an ounce from $27.40.

On the London Platinum and Palladium Market, platinum dropped to $1,425 an ounce from $1,514.

Palladium declined to $677 an ounce from $715.50.

OIL: London's Brent North Sea crude tumbled under $100 a barrel for the first time in nine months on concerns over slowing Chinese economic growth and weak energy demand, analysts said.

The contract slumped to $96.75 -- the lowest level since July 2 last year, on Thursday.

"The optimism of the first quarter of 2013 (shown by markets) is nowhere to be seen," said Tamas Varga, analyst at PVM oil brokers.

"It was the US that supported risky assets in the first three months of the year and it is the US that is responsible for the change in the sentiment. Disappointing job data turned the mood sour in April and of course the downgrading of China by Fitch and lower-than-expected Chinese GDP growth are not helping either.

"Throw in the negative global services and manufacturing data and the Cyprus/eurozone financial troubles and you'll end up with the perfect cocktail for a bear market," Varga added.

Concerns over weaker energy demand have also set in after the International Energy Agency and Organization of the Petroleum Exporting Countries (OPEC) recently lowered their global demand forecasts.

"At long last a little reality. Revisions in GDP and global forecasts for growth are all coming in line and lower," Jonathan Barratt, chief executive officer at Barratt's Bulletin in Sydney, told AFP.

"We still have significant bumps in the road in terms of recovery and the market is finally realising this."

Prices recovered slightly on Friday, with Brent briefly back above $100 on speculation that OPEC plans to cut output.

The oil-producing cartel earlier this month kept its global demand forecasts for 2012 and 2013 virtually unchanged, with China expected to contribute the most to growth while industrialised countries appeared to be headed for a decline.

Sanctions-hit Iran, OPEC's fourth largest producer, said on Wednesday that it considers the "logical" price of crude to be around $100-$120 a barrel.

Analysts said the $100 price for Brent is considered ideal by Saudi Arabia, the world's top oil exporter, and falling below it could prompt OPEC to cut back on output

By Friday on London's Intercontinental Exchange, Brent North Sea crude for delivery in June stood at $99.73 a barrel compared with $102.12 for the May contract a week earlier.

On the New York Mercantile Exchange, West Texas Intermediate (WTI) or light sweet crude for May slumped to $87.97 a barrel from $91.19.

BASE METALS: Base or industrial metal prices mostly retreated, with nickel hitting the lowest point for almost three years, at $15,180 a tonne.

"We are clearly in the throes of a massive sell-off in a number of complexes, as investors are rightly concluding that global growth prospects remain too tepid to sop up the growing surpluses evident in a number of sectors, including steel, aluminium and copper," said Edward Meir, an analyst at broker INTL FCStone.

"Moreover... macro numbers out of China are telling us that base metals cannot perpetually look to the country to be the ongoing prop for prices."

By Friday on the London Metal Exchange, copper for delivery in three months slid to $6,921 a tonne from $7,420 a week earlier.

Three-month aluminium grew to $1,885 a tonne from $1,858.

Three-month lead declined to $2,001 a tonne from $2,039.

Three-month tin dropped to $20,760 a tonne from $21,950.

Three-month nickel reversed to $15,221 a tonne from $15,850.

Three-month zinc climbed to $1,877 a tonne from $1,868.

COCOA: Cocoa futures extended recent gains.

"The pessimistic outlook of the International Cocoa Organization, which forecasts global deficits over the next few years for structural reasons, has caused the market to respond with price hikes," said analysts at Commerzbank.

By Friday on LIFFE, London's futures exchange, cocoa for delivery in July climbed to �1,554 a tonne from �1,487 a week earlier.

On New York's NYBOT-ICE exchange, cocoa for July rose to $2,342 a tonne from $2,243.

COFFEE: Arabica prices fell to an almost three-year low point of 133.55 US cents a pound at the start of the week in line with sliding markets, before recovering late on as a tree fungus in Central America continued to hit crops.

Leaf rust has caused coffee trees to produce fewer and lower-quality beans.

By Friday on NYBOT-ICE, Arabica for delivery in July firmed to 141.35 US cents a pound from 139 cents a week earlier.

On LIFFE, Robusta for July rose to $2,075 a tonne from $2,056.

SUGAR: Prices slid to a near three-year low of 17.43 US cents a pound in New York.

"The expected record sugar cane harvest that is now beginning in Brazil is continuing to cast its shadow," said analysts at Commerzbank.

By Friday on NYBOT-ICE, the price of unrefined sugar for delivery in July dropped to 17.55 US cents a pound from 17.78 cents a week earlier.

On LIFFE, the price of a tonne of white sugar for August edged higher to $500.50 from $498.70.

RUBBER: The price of rubber hit a five-month low point on rising Chinese inventories and expectations that the world's biggest rubber consumer would slash purchases, traders said.

The Malaysian Rubber Board's benchmark SMR20 slid to 234.40 US cents a kilo from 257.40 cents a week earlier.

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