A traffic jam of more than 130 cargo ships loaded with Ukrainian grain is waiting in the Black Sea to pass into the Danube as negotiators from Moscow, Kyiv, the UN and Turkey hailed progress at talks in Istanbul on easing Ukrainian agricultural exports. The ships are waiting to access exit routes through the Sulina and Bystre estuary canals to reach a series of ports and terminals in Romania from where the grain can be transported on around the world, amid mounting global concern about the Russian blockade on Ukrainian exports through the Black Sea. Maritime tracking services showed a logjam of ships waiting to pass into the Danube since a second route through the Bystre estuary was opened after the recent Russian retreat from the nearby Snake Island. Previously, ships had been able to pass into the Danube only via the Sulina canal, whose passage is one-way, with cargo vessels having to wait weeks to pass through. Although large carriers cannot pass through the Bystre estuary, limiting the amount of grain that can be exported, Ukrainian officials said on Wednesday that already 16 ships had transited the Bystre route in the four days since it reopened. With mined ports and a Russian blockade on Ukraine’s south coast limiting maritime traffic, the northern branch of the Danube delta, which follows Ukraine’s southern border, and small riverine ports have taken on global importance amid warnings of famine in parts of Africa as Ukraine’s grain has been kept from the international market and prices have rocketed. Until recently, the Bystre estuary route had been closed, but that has changed with the removal of Russian forces from Snake Island. “Given the liberation of Zmiinyi [Snake] Island from Russian troops and the buildup of a large number of ships waiting to proceed through the Sulina canal, it is possible to use the channel of the Bystry estuary of the Danube-Black Sea waterway for the entry/exit of ships transporting agricultural produce,” the Administration of Sea Ports of Ukraine said in a statement at the weekend. Ukrainian officials hope that the new route for grain exports will allow an additional 500,000 tons to be exported, although that will still be far short of the amount of grain that was exported before the Russian invasion. The capacity of the new routes is “currently insufficient to replace seaports fully”, Ukrainian officials noted. In June Ukraine exported about 2.5m metric tons of goods, far short of the 8m metric tons it had hoped to export, the infrastructure ministry said. Ukraine is the world’s leading wheat exporter, accounting for 9% of the global market. It also accounts for 42% of the sunflower oil market and 16% of world corn production. Owing to Russia’s blockade of Black Sea ports and a plethora of mines along the coast, 20m to 25m tons of wheat are stuck in Ukraine, pushing up world grain prices. Russia and Ukraine met UN and Turkish officials on Wednesday in an attempt to break the months-long impasse over grain exports. Russia’s invasion of Ukraine shows no signs of abating and the sides remain locked in a furious long-range shooting battle that is destroying towns and leaving people with nothing. The Istanbul negotiations – the first face-to-face talks between Russian and Ukrainian delegations since 29 March – are being complicated by growing suspicions that Russia is trying to export grain it has stolen from Ukrainian farmers in regions under its control. Turkey’s defence minister Hulusi Akar said an agreement would be signed next week. He said Ankara will ensure the safety of shipments in transit and the parties will jointly check grain cargoes in ports. But the UN secretary-general António Guterres said more work was needed before a deal was signed. US space agency data released last week showed 22% of Ukraine’s farmland had fallen under Russian control since the invasion began on 24 February. Ukraine’s foreign minister, Dmytro Kuleba, said Kyiv was “two steps from an agreement with Russia”. “We are in the final stages and everything now depends on Russia,” he told Spain’s El País newspaper. Russia said its requirements included the right to “search the ships to avoid the contraband of weapons” – a demand rejected by Kyiv. On Tuesday, Guterres tried to play down expectations of an imminent breakthrough. “We are working hard indeed, but there is still a way to go,” he said.