* Sugar trade awaits Unica Brazil cane data at 1700 GMT
* Favourable W. Africa crop weather weighs on cocoa
* Robusta coffee trades around 16-month low (Updates prices; adds comment, NEW YORK dateline, byline)
By Carole Vaporean and David Brough
NEW YORK/LONDON, June 11 (Reuters) - ICE raw sugar futures eased to their lowest level in about three years, pressured by a huge harvest in top grower Brazil, before the release of Brazilian cane industry data due later on Tuesday.
Arabica coffee dropped under pressured from surplus supply, and ICE cocoa was down in light volume against a backdrop of favourable crop weather in West Africa.
July raw sugar futures on ICE fell 0.15 cent, or 0.92 percent, to 16.23 cents a lb by 11:38 a.m. EDT (1538 GMT), having earlier eased to 16.18 cents, the lowest for the front month since July 2010.
Dealers anxiously awaited data from Brazilian cane industry group Unica at 1700 GMT for trends in the allocation of Brazilian cane to sugar and ethanol biofuel.
Some traders said that if the allocation of Brazilian cane favoured sugar instead of ethanol, this could be a signal for further declines in sugar prices.
"What the market wants to see is a mix running at well below 42 percent sugar to prove millers are favouring ethanol production and reducing sugar output," said Nick Penney of broker Sucden Financial Sugar.
"This may be a catalyst for some short covering, given the spec short position and the oversold condition of the market. We shall see."
Michael McDougall, a vice president for brokers Newedge USA in New York, pointed out that UNICA's second half of its May crush progress report has a range of crush estimates "that are all over the place with 32.5 to 39 million tons being cited by reputable groups."
He noted that the end of the two week period saw several days of rain that impacted the heart of Brazil's Center South.
August white sugar on Liffe was down $1.9 or 0.4 percent at $477.30 a tonne, with volume of 1,2,573 lots.
July arabica coffee futures on ICE eased 1.75 cent, or 1.36 percent, to $1.27 per lb.
The contract fell to $1.2505 per lb on May 31, the lowest level for the front month since September 2009, driven down by plentiful supplies.
Despite Monday's gains in coffee, dealers said arabica prices remained pressured by expectations of a huge off-year crop in top grower Brazil.
"Every time you see some technical resistance, there is a temptation to test it," said Ricardo Santos, senior coffee trader at Equatorial Traders.
September robusta coffee futures on Liffe fell $26, or 1.4 percent, to $1,831 a tonne, having earlier touched a 16-month low of $1,830, weighed down by plentiful supplies from top producer Vietnam and pressure from the arabicas market.
Cocoa on ICE edged lower on signs of healthy supply, with September settled down $4 at $2,364 a tonne in volume of 20,503 lots.
Cocoa arrivals at ports in top grower Ivory Coast reached around 1,260,000 tonnes by June 9 since the start of the season in October, exporters estimated on Monday, up from 1,190,000 tonnes in the same period of the previous season.
"Solid cocoa arrivals and good weather have reinforced the idea that the supply side is not problematic," said Eric Sivry, head of agri options brokerage at Marex Spectron.
Liffe September cocoa dipped 5 pounds to settle at 1,554 pounds a tonne in moderate volume of 7,996 lots. (Reporting by David Brough in London and Carole Vaporean in New York; editing by Jeff Coelho, William Hardy and Marguerita Choy)