GRAINS-Corn, soybeans rise for 3rd day on strong demand, short-covering

* Corn, soybeans gain more ground on short-covering

* Wheat dips after climbing more than 6 pct in 2 sessions (Adds comment, detail)

SINGAPORE, Oct 17 (Reuters) - Chicago corn and soybean futures rose for a third consecutive session on Monday, with prices underpinned by short-covering and strong demand.

Wheat was little changed as the market took a breather after climbing more than 6 percent in the last two sessions in an exports-driven rally.

The Chicago Board of Trade’s most-active corn contract had added 0.6 percent to $3.56-1/4 a bushel by 0157 GMT, having gained 1.4 percent on Friday to its highest in nearly three months at $3.58-3/4 a bushel.

Soybeans rose 0.6 percent to $9.67-3/4 a bushel and wheat was unchanged at $4.21 a bushel.

“Investors still hold a very large short position (in the corn market)”, said Tobin Gorey, director of agricultural strategy at Commonwealth Bank of Australia.

“Any further price strength today is likely to prompt another wave of short covering.”

Large speculators trimmed their net short position in CBOT corn futures in the week to Oct. 11, regulatory data released on Friday showed.

The Commodity Futures Trading Commission’s weekly commitments of traders report also showed that noncommercial traders, a category that includes hedge funds, trimmed their net short position in CBOT wheat and raised their net long position in soybeans.

There was additional support for the soybean market on Friday from higher soyoil values.

U.S. corn export sales this season were off to their strongest start in nearly a decade as low prices and limited export competition have expanded U.S. market share after years of ceding sales to suppliers like Brazil and Ukraine. Prices of the grain almost halved over the past three years.

The wheat market has been driven higher by strong global demand.

There were a spate of wheat purchases and tenders last week from buyers including Syria, Egypt, Algeria and Saudi Arabia. (Reporting by Naveen Thukral; Editing by Joseph Radford)