U.S. rice falls on Cambodia, soy up on supply woes

TOKYO (Reuters) - U.S. rice futures fell by the 50-cent limit on Tuesday after Cambodia lifted an export ban, while soybean futures jumped more than 1 percent on supply fears following a long-running farmers' dispute in Argentina.

Traders said Cambodia's decision to lift the two-month export ban on Monday and expectations that Vietnam would lift curbs from July were signs that rice supplies were likely to improve, helping world prices to ease from record levels.

"The lifting of the ban is having some impact on prices," said Vijay Iyengar, managing director of Agrocorp International Pte Ltd, a Singapore-based commodities trading firm.

U.S. rough rice futures on the CBOT fell 2.5 percent, or down by the 50-cent-limit, to $19.85 per hundredweight, carrying over the downward trend from Friday.

Chicago Board of Trade soybeans, corn and wheat futures advanced as bullish crude oil prices and a weaker dollar prompted fund inflows into the grains market.

"The market is worried about supplies from Argentina, keeping soy prices strong," said Kenji Kobayashi, a grains analyst at Kanetsu Asset Management in Tokyo.

"Uncertainty is especially big for the nearby contract, keeping the market in a backwardation."

The soybean contract for July delivery rose as high as $13.85 per bushel, up 1.2 percent from Friday's U.S. close of $13.68. U.S. markets were closed for a public holiday on Monday.

Concerns following a labor strike in Argentina have been boosting grain and oilseed prices.

The Argentine government has called off talks with farmers scheduled for Monday, a day after farm leaders angry at a tax on soy exports held the biggest protest yet against the current administration.

Argentine farm leaders demanded a new government farm policy in front of a crowd of more than 200,000 people on Sunday, showing strength ahead of negotiations to resolve the three-month-old conflict over soy taxes.

"The general uptrend in the grains market remains," Kobayashi said. "There is still momentum in the market, helped by the strength in oil prices and the bearish dollar."

Key U.S. crude oil futures held above $133 a barrel on Tuesday as long-term supply concerns lingered and fresh production problems appeared in Nigeria and Norway.

Oil prices have risen nearly 40 percent this year, reaching a record high of above $135 last week.

The dollar held its ground on Monday, taking advantage of the ultra-thin volumes owing to U.S. and UK market holidays to arrest its decline of the last three weeks and squeeze out slender gains against a basket of major currencies.

July CBOT corn was trading up 4-¾ cents at $6.04-½

per bushel from Friday's close of $5.99-3/4. It briefly touched a session high of $6.07 on Tuesday.

(Reporting by Chikafumi Hodo; Editing by Clarence Fernandez)