Commodities prices on Thursday extended their losses, with crude oil in New York approaching the $70 a barrel level, amid mounting fears that recent government and central bank actions to unfreeze credit markets will fail to avert a global recession.

Copper, the base metals bellwether, tumbled to a 34-month low on concerns that the previously booming global construction business is coming to a halt.

In mid-morning trading in London, Nymex November West Texas Intermediate fell $2.25 to $72.79 a barrel. Earlier it hit a 13-month low of $71.21 a barrel. ICE November Brent fell $3.14 to $67.66 a barrel.

Natural gas, heating oil and gasoline prices also posted large losses.

Olivier Jakob, of Swiss-based consultant Petromatrix, said: "If the global markets are not able to provide a 'V-shaped' recovery and global deleveraging continues, the [oil price] risk for the next 30 days is clearly skewed to the downside."

The fresh price falls came a day after Opec, the oil cartel, warned of "dramatically worsening conditions" in the credit market and a "negative impact on the real economy", and Rio Tinto, one of the world's largest mining companies, signalled that Chinese commodities demand was weakening.

In its monthly report, the cartel said that even if governments were successful in unfreezing credit markets in the near future, "the fallout on the real economy from the financial market headwinds is expected to be considerable".

Base metals also extended their losses, with copper for delivery in three months at the London Metal Exchange dropping 3.5 per cent to $4,650 a tonne. Earlier, copper fell to $4,545 a tonne, the lowest level since January 2006.

Lead dropped 5.5 per cent to $1,415 a tonne while zinc tumbled 7.2 per cent to $1,206 a tonne.

Spot gold prices in London were $10 down to $835.15 a troy ounce as investors worried about a global recession sold commodities baskets products that, among other raw materials, include bullion.

Gold prices have weakened in the last few days after surging above $925 an ounce. But physical demand continues to be strong, traders said, although at a slower pace.

Zurich Cantonal Bank said on Wednesday that its gold vault was full and it was seeking another secure deposit for its bullion-backed exchange traded fund after gold holdings hit a record 2.66 million ounces.

"Our vaults are full right up to the top," a spokesman told Bloomberg News.

Agricultural commodities were also lower in early trading, with CBOT December corn falling 7¾ a bushel to $3.80¼ a bushel.