* Sugar's ample supply prospects bearish for market
* Investors liquidate long positions in ICE cocoa
* Dealers expect arabica prices to fall in coming months (Adds details and recasts, changes dateline)
By Rene Pastor and David Brough
NEW YORK/LONDON, May 5 (Reuters) - Soft commodity futures were pummeled Thursday as the sugar, coffee and cocoa markets were caught up in a commodity-wide selling spree.
The Reuters-Jefferies CRB index, a global benchmark for commodities, was headed for its biggest loss in two years on widespread liquidation.
World stocks and crude oil prices fell on Thursday after a report showed U.S. jobless claims unexpectedly jumped to an eight-month high last week, fuelling demand for safe-haven assets.
"It's just a massive, macro liquidation," said Nick Gentile, the head of trading of commodity fund Atlantic Capital Advisors.
"The day's decline in agriculture is entirely related to broader markets," said Carsten Fritsch, commodity analyst at Commerzbank in Frankfurt, pointing to the sharp fall in oil and metal markets.
All the soft markets declined, with arabica coffee retreating further from the 34-year high it hit last week and raw sugar crumbling from investor sales.
New York's July cocoa contract dropped $156 or by 4.9 percent to end at $3,055 per tonne. London's July cocoa futures lost 60 pounds or by 3.1 percent to finish at 1,885 pounds per tonne.
The July raw sugar contract declined 0.40 cent to trade at 20.95 cents per lb at 12:10 p.m. (1610 GMT), while London's August white sugar futures fell $10.90 to trade at $581.80 per tonne.
The July arabica coffee contract on ICE Futures U.S. slid 7.80 cents to trade at $2.867 per lb at 12:14 p.m., having hit a session low of $2.841.
London's July robusta coffee was only down $2 to trade at $2,575 per tonne, having recovered from a session low of $2,521 during Thursday's session.
"It's almost snowballing, the spec liquidation across all of these markets now," said Luis Rangel, vice president for commodity derivatives with ICAP North America in New Jersey.
He said the sell-off kicked with the silver market, saying "it was sort of the ring leader and it's started to spread like a contagion."
Fundamentally, the soft markets present a mixed bag.
Coffee, especially the arabica market, must contend with tight supplies of high quality washed beans. Sugar could see cash activity pick up as prices tumble. Cocoa is looking at a pickup in exports after a civil war in top grower Ivory Coast.
Top coffee producer Brazil's harvest could also weigh on prices in the coming months, Rabobank's soft commodities analyst Keith Flury said.
Dealers said they expected Egypt to return to the market soon with a substantial buying tender, possibly as soon as this weekend, having cancelled a tender for 200,000 tonnes of raw sugar earlier this week.
"The physical market will dictate how low the futures will go," said James Kirkup, head of sugar brokerage at ABN AMRO (Markets) UK Ltd.
But analysts said bumper supplies flowing out of Brazil and also out of key exporter Thailand should keep the market under pressure.
"From what I am hearing, the centre-south Brazilian harvest is going off pretty well," Flury said.
"Prices for coffee and cocoa have to some extent been speculator driven. For these markets, this was a correction that was due," Fritsch said. (With additional reporting by Sarah McFarlane in London and Marcy Nicholson in New York) (Editing by Sofina Mirza-Reid)