Chicago wheat futures fell on Friday to a new one-week low after comments by Russian President Vladimir Putin revived hopes of a ceasefire in Moscow's war with Ukraine that has choked Black Sea grain exports.

Putin: 'Certain Positive Shifts'

Trading in wheat remained volatile as market participants wrestled with the possible extent of supply disruption from the war and knock-on demand for other suppliers like the European Union and the United States. U.S. stock index futures jumped after Putin said there were "certain positive shifts" in talks with Ukraine.

The most-active wheat contract on the Chicago Board of Trade (CBOT) was down 1.9% at $10.66-1/4 a bushel by 1249 GMT. It earlier rose to $11.26-1/4 to recover from a two-day slide, before turning lower to hit a new one-week low. "Putin's comments seem to have cooled the wheat market a bit," a European trader said.

Chicago wheat had already fallen sharply mid-week as traders saw the price surge since the start of the war in Ukraine as overdone and leaving U.S. exports uncompetitive. "The U.S. market is somewhat disappointed that more export sales have not been reported," said Tobin Gorey, director of agricultural strategy at the Commonwealth Bank of Australia.

In Europe, Paris-based Euronext saw smaller losses, with May wheat down 0.4% at 366.25 euros ($402.84) a tonne. Demand for EU wheat as an immediate replacement for Ukrainian and Russian supplies, which account for about 30% of global wheat exports, was underpinning the European market.

UN: Food, Feed to Rise 8%-20%

In a first assessment of the war in Ukraine, the U.N. food agency on Friday said international food and feed prices could rise by between 8% and 20%, and that 20% to 30% of fields used for major crops in Ukraine may go unplanted or unharvested.

CBOT corn was down 0.8% at $7.49-1/4 a bushel, while soybeans eased 0.7% to $16.73-3/4. CBOT corn and soybean had rallied on Thursday on signs of strong export demand for U.S. supplies following drought in South America, and amid the war in Ukraine.

However, beneficial rain in parts of Argentina and Brazil have curbed corn and soy prices.Wheat, corn and soy US cents/bushel, Paris futures in euros per tonne.

$1 = 0.9092 euros)