Chicago wheat futures dipped from three-month highs on Monday although the market was underpinned by crop concerns in Europe and escalating tensions between Russia and Ukraine.

Corn and soybean futures also fell as the United States geared up for large harvests of both crops.

The most-active wheat contract on the Chicago Board of Trade (CBOT) was down 1.6% at $5.85-1/2 a bushel by 1052 GMT having touched $5.99 on Friday, its highest since June 19.

Wheat has risen around 13% over the last three weeks, helped in part by a weak U.S. dollar that has made U.S. farm goods cheaper for overseas buyers.

"Crop reductions in the EU appear to be the main catalyst for the gains," said Rod Baker at Australian Crop Forecasters, adding that dry conditions in the Black Sea region are also hindering planting of winter wheat.

Soil moisture levels are depleted in much of Ukraine.

"There is room to delay planting through to October, but the near-term forecast shows no reprieve from the dryness," said Dennis Voznesenski of Commonwealth Bank of Australia in a note.

An alleged missile attack on a grain vessel in the Black Sea added to doubts about Russian and Ukrainian supply. Russia is the world's top wheat exporter and Ukraine a major shipper.

However, the U.S. Department of Agriculture (USDA) last week raised its estimate for global wheat ending stocks, limiting price gains, analysts said.

"We may see some more downward pressure on wheat prices when that big U.S. corn harvest starts," Baker said.

CBOT corn slipped 0.7% to $4.10-1/4 a bushel on Monday, while soybeans fell 0.15% to $10.04-3/4 a bushel.

The USDA last week raised its forecast for U.S. corn yields and production, which are expected to be the second largest in history, and trimmed its projection for U.S. soybean production, though the crop remains on track to be the biggest ever.

Speculators last week reduced short positions in CBOT corn, soybean and wheat futures but are still bearish on all three.

(Reporting by Peter Hobson in Canberra and Nigel Hunt in London; Editing by Rashmi Aich, Sumana Nandy and Susan Fenton)