CANBERRA, Sept 14 (Reuters) - Chicago wheat futures dipped on Thursday as concerns over supply from war-torn Ukraine were offset by large exports of cheap grain from Russia, keeping prices near 33-month lows.

Soybean and corn futures rose slightly.

FUNDAMENTALS

* The most-active wheat contract on the Chicago Board of Trade (CBOT) was down 0.1% at $5.96-3/4 a bushel, as of 0056 GMT. CBOT soybeans were up 0.2% at $13.53 a bushel and corn was 0.1% higher at $4.82-1/2 a bushel.

* Ukrainian grain exports plunged to 783,000 metric tons between Sept. 1 and Sept. 13 from around 1.5 million tons in the corresponding period in 2022, agriculture ministry data showed on Wednesday.

* The ministry gave no explanation for the fall, but Ukraine's deputy prime minister said more than 100 port infrastructure facilities had been damaged by Russian attacks since July 18.

* He said the export potential of Ukrainian ports on the Danube River has been cut by nearly 0.5 million tons of grain a month.

* Ukraine is stepping up road and rail shipments, but volumes are smaller and costs are higher.

* Meanwhile, Hungary said it had agreed with Romania, Slovakia and Bulgaria to bar Ukrainian grain imports to protect their markets if the European Union does not extend a ban that expires on Sept. 15.

* Worries about Ukrainian supply pushed Chicago wheat up 1.7% on Wednesday, although exports from Russia have boomed, keeping a lid on gains.

* Russian agricultural consultancy Sovecon this month raised its forecast for Russia's wheat exports to 48.6 million metric tons in the 2023/24 season.

* Elsewhere, Argentina's Rosario grains exchange trimmed its forecast for the 2023/2024 wheat harvest to 15 million metric tons from 15.6 million tons due to dry conditions in some areas.

* FranceAgriMer lowered its forecast of French soft wheat exports outside the European Union in 2023/24 by 100,000 metric tons to 9.5 million metric tons.

* Iran's Government Trading Corporation (GTC) is believed to have purchased about 240,000 metric tons of milling wheat from Russia in the past few weeks, traders said.

* The U.S. Department of Agriculture (USDA) is due to release weekly export sales data on Thursday, with analysts polled by Reuters expecting net wheat sales of 250,000 to 600,000 metric tons in the week ended Sept. 7.

* In soybean markets, the U.S. soybean crush in August likely increased from the same month last year, analysts said ahead of a monthly National Oilseed Processors Association (NOPA) report due on Friday.

* Chicago soybeans remain near a three-week low reached on Tuesday, when the USDA cut its forecast for U.S. soybean output in a monthly report by less than some analysts had expected.

* Commodity funds were net buyers of CBOT wheat soybean and corn futures on Wednesday, traders said.

MARKETS NEWS

Wall Street closed mixed on Wednesday after data showed that underlying inflation remained on a slow downward trajectory, cementing the likelihood that U.S. interest rates will remain unchanged for the time being.

(Reporting by Peter Hobson; Editing by Sherry Jacob-Phillips)