Ukraine, the United Nations and Turkey havae hailed progress at talks aiming to resume Black Sea grain exports blocked by Russia and ease the risk of starvation faced by millions.

But an end to the war remains far off as heavy shelling continued on Thursday.

Turkey’s Defence Minister Hulusi Akar said on Wednesday an agreement would be signed next week. Ankara will ensure the safety of shipments in transit and the parties will jointly check grain cargoes in ports, he added.

But UN chief Antonio Guterres said more work was needed before a deal was finalised.

“We have seen a critical step forward,” Guterres told reporters in New York. “We still need a lot of goodwill and commitments by all parties,” he said.

Ukrainian President Volodymyr Zelenskiy appeared optimistic in late-night comments: “The Ukrainian delegation has reported to me that there is progress. In the coming days we will agree on the details with the UN secretary general.”

Turkey and Ukraine said a joint coordination centre with Russia and the United Nations would be set up.

“Its task will be to carry out general monitoring and coordination of safe navigation in the Black Sea,” Zelenskiy’s Chief of Staff Andriy Yermak said on Twitter.

Apart from being major global wheat suppliers, Russia is also a large fertiliser exporter and Ukraine a significant producer of corn and sunflower oil.

A deal is seen as vital for food security, notably among developing nations, and for stabilising markets.

But Guterres warned there was still “a long way to go” before there would be peace talks to end the war.

Ukrainian officials said there had been sustained shelling across several cities.

Russian forces targeted a number of civilian facilities in the southern city of Mykolaiv on Thursday, Mayor Oleksandr Senkevych said on the messaging app Telegram. 

In the industrialised Donbas region of eastern Ukraine, Russian missiles hit the industrial zone of Kramatorsk and electricity was cut in some parts of the city, Mayor Oleksandr Honcharenko wrote on Facebook.

A Russian strike destroyed a school in Donbas on Wednesday. No casualties were reported.

“All this makes me feel sick … Monsters, simply monsters, there is no other word. A school – if they themselves are ok to grow up stupid, why bomb our schools?” said 60-year-old resident Oleksandr.

Russian media reported Ukrainian armed forces launched a fresh missile attack in a strategically important Russian-held southern area of Kherson that Kyiv is hoping to retake.

RIA news agency quoted the Russian-backed administration of Kherson region as saying Russian air defenses shot down five missiles fired at the town of Nova Kakhovka, while the debris of two of the missiles fell near a factory.

“According to preliminary information, there’s been another hit on a Russian munitions plant, at Sokil,” Serhiy Khlan, an adviser to the Ukrainian head of Kherson province, wrote on Facebook.

On Wednesday TASS quoted a separatist official, Vitaly Kiselyov, as saying Russian and proxy forces had entered the town of Siversk in Donetsk province and could take it in a couple of days.

Donetsk and Luhansk comprise the Donbas region.