Russia's Veterinary and Phytosanitary Surveillance Service (VPSS) says it will suspend Ukrainian soy, soymeal, and sunflower seed imports starting from August 1.
The Interfax news agency cited the service as saying the move was prompted by a breach of phytosanitary requirements.
Ukraine exported 1.2 million tonnes of soy in 2013, of which 141,000 tonnes went to Russia, according to Ukragroconsult consultancy data. Russia had previously banned Ukrainian dairy and juice supplies from July 29.
Russia has also restricted imports of fruits and vegetables from Poland, and banned fruit imports from Moldova.
The European Union and the United States imposed sanctions targeting broad sectors of Russia's economy this week over its alleged support for separatists fighting government forces in eastern Ukraine.