The Turkish bulk carrier Osprey S, flying the flag of Liberia, was expected to arrive in Ukraine's Chornomorsk port on Friday, the regional administration of Odesa said. It would be the first ship to arrive at a Ukrainian port during the war.
As of Thursday afternoon, Osprey S was anchored in the Sea of Marmara, around 1 km (0.62 mile) off Istanbul's Asian coast, along with other ships waiting to cross the Bosphorus in to the Black Sea, according to a Reuters journalist.
Russian President Vladimir Putin sent troops into Ukraine on 24 February, sparking the biggest conflict in Europe since World War Two and causing a global energy and food crisis. Ukraine and Russia produce about one third of global wheat and Russia is Europe's main energy supplier.
Eastern fighting hell
After five-months of fighting, Ukrainian President Volodymyr Zelenskiy this week described the pressure his armed forces were under in the eastern Donbas region as "hell".
Moscow is seeking to control the largely Russian-speaking Donbas, comprised of Luhansk and Donetsk provinces, where pro-Moscow separatists gained control of territory after the Kremlin annexed Crimea to the south in 2014.
Zelenskiy spoke of fierce fighting around the town of Avdiivka and the fortified village of Pisky, where Kyiv has acknowledged its Russian foe's "partial success" in recent days.
The Ukrainian military said on Thursday Russian forces had mounted at least two assaults on Pisky but had been repelled.
Ukraine has spent the last eight years fortifying defensive positions in Pisky, viewing it as a buffer zone against Russian-backed forces who control the city of Donetsk about 10 km to the southeast.
Ukrainian General Oleksiy Hromov told a news conference his forces had recaptured two villages around the eastern city of Sloviansk, but had been pushed back to the town of Avdiivka after being forced to abandon a coal mine regarded as a key defensive position.
The Russian defence ministry confirmed its offensive.
Reuters could not immediately verify either side's assertions.
The Ukraine war has displaced millions, killed thousands of civilians, and left cities, towns and villages in rubble. Kyiv and its Western allies have accused Russian forces of targeting civilians and war crimes, charges Moscow rejects.
NATO chief warns Putin
Human rights group Amnesty International on Thursday said Ukraine was endangering civilians by basing troops in residential areas.
Zelenskiy hit back at Amnesty saying the organisation was trying to "shift responsibility from the aggressor to the victim."
The White House said on Thursday that it expected Russian officials to try and frame Ukrainian forces for an attack on the front-line town of Olenivka last week that killed prisoners held by Moscow-backed separatists.
Russia's deputy UN ambassador responded in a Twitter post, saying US-made High Mobility Artillery Rocket Systems were used in the attack.
UN Secretary General Antonio Guterres said on Wednesday he will launch a fact-finding mission after Russia and Ukraine both requested an investigation.
Putin says he launched his "special military operation" in Ukraine to ensure Russian security and protect Russian-speakers in Ukraine. Kyiv and the West describe Russia's actions as an unprovoked imperial-style war of aggression.
NATO Secretary-General Jens Stoltenberg said on Thursday the war was the most dangerous moment for Europe since World War Two and that Russia must not be allowed to win. Read full story
Amid fears among some politicians in the West that Russia's ambitions may extend beyond Ukraine, Stoltenberg warned Putin that the response to such a move from the Western military alliance would be overwhelming.
"If President Putin even thinks of doing something similar to a NATO country as he has done to Georgia, Moldova or Ukraine, then all of NATO will be involved immediately," Stoltenberg said.
The war has led previously non-aligned Finland and Sweden to seek NATO membership, with the request so far ratified by 23 of the 30 member states, including the United States.