Xstrata - Global Mining Group

LONDON (Reuters) - Copper prices tumbled below $6,000 a tonne on Wednesday, their lowest since April last year, as rising stocks fuelled worries about a surplus this year, analysts said.

The losses dragged down other base metals and weighed on London-listed miners such as BHP Billiton, Antofagasta, Kazakhmys, Rio Tinto and Xstrata, which were all down between 2 and 5 percent.

Copper for delivery in three months on the London Metal Exchange traded at $5,910, its lowest in nearly nine months. By 1132 GMT it was quoted at $5,915/5,930, down more than 3.0 percent from Tuesday's $6,110 close.

Copper has lost more than 30 percent since hitting a record high of $8,800 in May and more than 25 percent since early September on growing worries about falling demand as global economic growth slows.

Forecasts of a copper surplus this year have accelerated losses.

"Clearly the increase in inventories has got people worried. We're (forecasting) a surplus of about 250,000 tonnes this year," Jim Lennon, analyst at Macquarie Bank, said.

"People are saying it's all over as far as copper is concerned and clearly it is. Our price forecast this year is $2.60 a pound."

That would work out to an average around $5,730 this year.

DEBATE

Stocks of copper at LME warehouses have risen to more than 190,000 tonnes from little more than 25,000 in July 2005.

On Tuesday copper stocks jumped 7,775 tonnes and on Wednesday the rise was 1,975.

"Today's number wasn't as bad as people thought it would be and that gave copper a reprieve," an LME trader said. "But it didn't last long, I think it's gone into oversold territory and will probably bounce back."

By that was a matter of debate, analysts said. Those expecting a hard landing in the United States think copper might soon be hurtling towards $5,000 if U.S. manufacturing and jobs data later this week are weaker than forecast.

Others are more positive.

"Economic data out of the U.S. in the last few weeks has tended to beat expectations and there is even some talk that the worst of the slowdown in the housing market may have passed," BaseMetals.com said in a research note.

"That said, the more copper prices do fall the more likely they are to run into consumer buying."

But for now consumers seemed to be content watching from the sidelines and were in no hurry to restock, analysts said.

When consumers did return, prices might spike up as funds that were short -- a bet on a lower price in the future -- bought back the contracts they had sold, analysts said.

Aluminium was down at $2,711/2,716 from $2,787 on Tuesday, nickel was at $31,900/32,100 from $32,475 and zinc was at $4,050/4,080 from $4,130.