The copper price slid more than 2% on Tuesday, nearing a three-year low.

Spot copper prices fell 6c a pound to $3.03 in New York afternoon trade on Tuesday as worries over Chinese demand persist and supply forecasts continue to rise.

China is responsible for 42% of total global copper demand of 20.5 million tonnes, and worries about slowing growth in the world's second largest economy has pushed down price for the red metal by close to 16% this year.

A number of new forecasts show an increased risk of a sharp slowdown in China which this year is expected to record a still robust 7.5%, down from years of double digit growth in the past.

Bloomberg reports Japan's Nomura Holdings estimates a one-in-three chance of a sharp drop to below 5% by the end of 2014 adding that GDP growth of less than 6% in 2014 would lead metal prices to fall as much as 30%.

French investment bank Societe Generale SA sees a "non-negligible risk" of a slowdown to less than 6% as soon this year and "an outside chance of 3 percent average expansion for this half and next".

For its part the UK's Barclays economists said a scenario in which quarterly growth drops "briefly" to 3% at some point in the next three years was "increasingly likely" and although it is likely that China will bounce back quickly the impact on copper and other metal prices would be severe.

A report in Barrons.com outlines how the supply outlook is equally bearish with Citi analysts predicting the globe's total copper supply will increase 5.4% or 900,000 tonnes in 2013, up from 3.2% growth last year:

At the same time, production disruptions in the copper industry have been unusually light this year, helping to ramp up output. None of the mega-mines in Chile, which supplies about a third of the world's copper, have suffered a protracted setback in 2013. Analysts typically expect between 5% and 8% of expected supply to be lost to various disruptions.

Even a massive landslide in April at Rio Tinto's Bingham Canyon mine didn't dent much of the output onslaught. Work restarted just 17 days later. The company initially estimated it would lose about 100,000 tons of output due to the accident, but analysts now say lost production is likely to be a quarter of that.