LONDON, Nov 3 (Reuters) - ICE raw sugar futures jumped to a nine-month high on fund buying and trade short covering on Tuesday, while robusta coffee eased due to the onset of the harvest in top producer Vietnam.

Cocoa was little changed in light volumes, underpinned by concerns over the potential impact of dry weather on main crop production in leading growers Ivory Coast and Ghana.

Raw sugar futures hit the nine-month peak of 15.33 cents a lb on buying triggered by a lower than expected increase in speculators' net long position, combined with wet weather hampering cane harvesting in centre-south Brazil.

"With the rains there will be a dilution of the sugar content and a likely increase in allocation of cane to ethanol," said Tracey Allen, a commodity analyst with Rabobank.

Dealers also referred to trade short covering on the view that India was unlikely to emerge as a major raw sugar exporter this season.

ICE spot raw sugar futures traded up 0.17 cents, or 1.1 percent, at 15.28 cents per lb at 1226 GMT, after touching 15.33 cents, the highest since late January.

December white sugar futures were up $3.20, or 0.8 percent, at $410.70 per tonne.

Robusta coffee futures eased, weighed down by the start of the harvest in Vietnam and a stronger dollar.

January robusta coffee traded down $8, or 0.5 percent, at $1,621 per tonne.

"Any additional selling pressure could see moves on the downside breach $1,600 and then target the moving averages around $1,590," said Kash Kamal, senior research analyst with Sucden Financial Sugar.

December arabica traded down 0.7 cents, or 0.6 percent, at $1.181 per lb, weighed down by the firmer dollar which makes the dollar-based commodity more expensive in terms of other currencies.

New York March cocoa were down $13, or 0.4 percent, at $3,282 per tonne, having touched a five-week high of $3,299 per tonne on Monday.

London March cocoa futures were down 1 pound, or 0.05 percent, at 2,204 pounds a tonne. (Editing by David Evans)