* NY cocoa plummets to mid-2013 low on strong supply
* Raw sugar firms slightly after Tuesday's price surge
* Arabica extends losses below key technical levels (Rewrites throughout, updates prices; adds comment, second byline, NEW YORK dateline)
By Marcy Nicholson and Helen Reid
NEW YORK/LONDON, Dec 7 (Reuters) - New York cocoa futures hit their lowest in more than three years on Wednesday, as traders expect abundant global supplies, also pressuring the London market to a 2-1/2-year trough and taking it to the most technically oversold level in five years.
Sugar consolidated after Tuesday's sharp rally while arabica coffee fell to its lowest since August.
In cocoa, plentiful supplies from top grower Ivory Coast helped push prices even lower, with no sign of respite even though the markets were oversold.
"We have seen selling with impunity. There has been a surprisingly strong decline without prospects of a relief bounce," said a cocoa broker.
Arbitrage between the markets pushed New York cocoa lower, he said, with London dictating the pace.
March New York cocoa settled down $34, or 1.4 percent, at $2,324 per tonne, after touching $2,295, the weakest since August 2013.
March London cocoa fell for its 11th straight session, closing down 12 pounds, or 0.64 percent, at 1,861 pounds per tonne, after reaching 1,837 pounds, the lowest since May 2014.
"The fundamentals still indicate increased supplies, and the commercials have been able to buy at much cheaper prices," said Jack Scoville, vice president with Price Futures Group in Chicago.
"Ideas of bigger production in West Africa and reports of weaker cash market prices continue."
Voting got underway in elections in Ghana, the second largest cocoa producer, in what looked to be a tight race.
Sugar prices were mixed, with raws firming slightly after Tuesday's sharp rally from a four-month low.
The run higher was partly fueled by news of Brazil's Petrobras hiking wholesale gas and diesel prices by 8.1 and 9.5 percent respectively, seen as making ethanol more competitive for mills to produce instead of sugar.
March raw sugar settled up 0.12 cent, or 0.6 percent, at 19.63 cents per lb. March white sugar settled down 20 cents, or 0.04 percent, at $519.70 per tonne.
Arabica coffee futures, which have been weakened by oversupply, extended losses below their 200-day moving average at 61.8 percent Fibonacci retracement level.
March arabica settled down 0.3 cent, or 0.2 percent, at $1.417 per lb, after reaching $1.4075, the lowest for the second-position contract since mid-August.
January robusta coffee settled down $9, or 0.4 percent, at $2,030 per tonne.
Rains in Vietnam delayed the robusta harvest and Brazil's coffee exports, mostly arabica, in November were down from a year ago. (Editing by David Evans and James Dalgleish)