Russia said Monday it was suspending its participation in a crucial deal that allowed the export of Ukrainian grain, once again raising fears over global food supplies and scuppering a rare diplomatic breakthrough to emerge from Moscow's war in Ukraine.

The agreement, brokered by Turkey and the United Nations in July 2022, was officially set to expire at 5 p.m. ET on Monday (midnight local time in Istanbul, Kyiv, and Moscow).

Kremlin spokesperson Dmitry Peskov told reporters on Monday that Russia would not renew the pact right now, saying it "has been terminated."

Russia has for some time complained that it is being prevented from adequately exporting its own foodstuffs, and Peskov cited that objection as the reason for pulling out of the deal. "As soon as the Russian part is completed, the Russian side will return to the implementation of this deal immediately," he told reporters.

Over the weekend, Russian President Vladimir Putin said that the main objective of the deal -- supplying grain to countries in need -- "has not been realized," again complaining that Russia faced obstacles exporting its own food.

US Secretary of State Antony Blinken last week accused Russia of using the grain deal "as a weapon."

The deal allowed Ukraine to export grain from its ports and navigate safe passage through the Black Sea, to Turkey's Bosphorus Strait.

It proved vital for stabilizing global food prices and bringing relief to the developing countries which rely on Ukrainian exports.

When asked, Peskov denied that Russia's decision to allow the deal to lapse was related to Ukraine's claimed strike on the bridge connecting mainland Russia to occupied Crimea on Monday. "These are absolutely unrelated events," he said.

Moscow had threatened to pull out of the deal on previous occasions. The pact was on the brink of breaking down in late October and early November 2022 when Russia suspended its participation over drone attacks on the city of Sevastopol. However, Moscow decided to reverse course following mediation.