Russia said on Monday that it was pausing its participation in an agreement that had allowed Ukraine to export its grain by sea despite a wartime blockade, upending a deal seen as essential to keeping global food prices stable.

The announcement appeared to be the most serious blow yet to a year-old agreement that had been a rare example of fruitful talks between the warring nations and had helped to alleviate part of the global fallout from Russia’s full-scale invasion. Ukraine is a major producer of grain and other foodstuffs, and the UN had warned that some countries in West Asia and Africa faced famine if Kyiv could not export its goods via the Black Sea.

A Kremlin spokesman, Dmitri S. Peskov, told journalists on Monday that the agreement was “suspended”, but added that the decision was not connected to the attack hours earlier on the Kerch Strait Bridge linking Russia to occupied Crimea. Russian officials blamed Ukraine for the bridge attack, but Kyiv has not taken responsibility.

Speaking about the grain agreement, Peskov said: “As soon as the Russian part is fulfilled, the Russian side will immediately return to the implementation of that deal.”

Russia has repeatedly complained about the agreement, which it considers one-sided in Ukraine’s favour. Russia’s foreign ministry on Monday issued a statement that emphasised its objections, including what it described as continued Ukrainian “provocations and attacks against Russian civilian and military facilities” in the Black Sea area, and said that the UN and Ukraine’s western allies had not addressed Russian demands.

“Only upon receipt of concrete results, and not promises and assurances, will Russia be ready to consider restoring the ‘deal,’” the statement said.

The deal, known as the Black Sea Grain Initiative and brokered by the UN and Turkey, had been set to expire on Monday. Turkey’s President, Recep Tayyip Erdogan, said he would speak to President Vladimir V. Putin of Russia about the agreement and signalled hope that he would agree to rejoin it.

New York Times News Service