* Corn up 1.5% as supply worries drive prices to 8-year high * Wheat gains 2.4% to seven-year high, soybeans at 2013 peak (Adds quote in paragraph 3, French crop conditions, CFTC positions) SINGAPORE, April 26 (Reuters) - Chicago corn futures jumped on Monday to their highest since June 2013, as concerns over global supplies buoyed the market. Wheat gained 2.4% to a seven-year top, while soybeans hit an eight-year high. “Corn is in the driver’s seat as there are supply worries as well as strong demand,” said one Singapore-based feed grains trader. “Corn is pulling prices of wheat and soybeans higher.” The most-active corn contract on the Chicago Board of Trade (CBOT) rose 1.5% to $6.42-1/4 a bushel by 0251 GMT, having earlier hit a June 2013 high of $6.49 a bushel. Dryness in Brazil and a cold spell in the United States raised supply concerns in the world’s two biggest corn exporters, while stocks from the 2020 harvest have been dwindling and demand from China has been growing. The condition of French wheat and barley crops deteriorated marginally for a second week but was still good, data from farm office FranceAgriMer showed on Friday, suggesting a moderate impact so far from recent cold, dry spells. An estimated 85% of French soft wheat was in good or excellent condition in the week to April 19, down from 86% the prior week and 87% two weeks earlier, according to FranceAgriMer’s cereal crop progress report. Meanwhile, officials in Argentina, the world’s No. 3 corn supplier and top exporter of soymeal livestock feed, are considering an increase in grains export taxes. Soybeans were up 0.6% at $15.24-3/4 a bushel, after climbing to the highest since June 2013 at $15.40 a bushel, while wheat hit $7.32 a bushel, the highest since May 2014. Large speculators cut their net long position in CBOT corn futures in the week to April 20, regulatory data released on Friday showed. The Commodity Futures Trading Commission’s weekly commitments of traders report also showed that non-commercial traders, a category that includes hedge funds, trimmed their net short position in CBOT wheat and raised their net long position in soybeans. (Reporting by Naveen Thukral; Editing by Subhranshu Sahu)