ISTANBUL (Reuters) -- Turkey announced a deal with Ukraine, Russia and the United Nations on Wednesday aimed at resuming Ukrainian grain exports blocked by Russia, raising prospects for an end to a standoff that has exposed millions to the risk of starvation.
Turkish Defense Minister Hulusi Akar said the deal would be signed when the parties meet again next week and included joint controls for checking grains in ports and Turkey ensuring the safety of Black Sea export routes for Ukrainian grain.
Turkey would also set up a coordination center with Ukraine, Russia and the United Nations for grain exports, he said.
Ukraine, which was invaded by Russia in February in what has become Europe's biggest conflict since World War II, had said earlier that a deal appeared just "two steps away" as Turkey hosted the four-way talks in Istanbul.
U.N. Secretary General Antonio Guterres said a "critical step forward" had been made toward reviving Ukrainian grain exports but cautioned that "more technical work will now be needed to materialize today's progress".
"Today is an important and substantive step, a step on the way to a comprehensive agreement". Ukraine and Russia had shown they could talk, but "for peace, we still have a long way to go," he told reporters in New York.
There was no immediate comment from Ukraine or Russia, both among the world's largest grain exporters.
Russia's Interfax news agency quoted Pyotr Ilyichev, head of the international organizations department at Russia's foreign ministry, earlier on Wednesday as saying Russia wanted to control and inspect vessels itself to rule out arms smuggling.
Several Ukrainian cities, meanwhile, reported heavy Russian shelling and, while not linking a grain deal to progress in talks to end the war, Ukrainian Foreign Minister Dmytro Kuleba was downbeat on prospects for peace.
More than 20 million tonnes of Ukrainian grain are stuck in silos at the Black Sea port of Odesa and dozens of ships have been stranded due to Russia's blockade, part of what Moscow calls its "special military operation" in Ukraine, but which Kyiv and the West say is an unjustified war of aggression.
The talks, in Istanbul between Ukrainian, Russian, Turkish and U.N. officials, took place behind closed doors at an undisclosed location.
Igor Konashenkov, a spokesperson for Russia's defense ministry, said Moscow had put forward proposals to resolve the grain issue as soon as possible.
Turkey published a photograph of the meeting showing the Russian and Ukrainian delegations sitting opposite each other looking stony-faced.
Apart from being major global wheat suppliers, Russia is also a large fertilizer exporter and Ukraine a significant producer of corn and sunflower oil. So, clinching a deal to unblock exports is seen as vital for food security, notably among developing nations, and for stabilizing markets.