Three ships loaded with grain have left Ukrainian ports under a recently concluded safe-passage deal.
The first grain ship to set sail from a Ukrainian port since the start of the Russian invasion departed Odessa on Monday.
"We expect that the security guarantees of our partners from the UN and Turkey will continue to work, and food exports from our ports will become stable and predictable for all market participants," Ukrainian Infrastructure Minister Oleksandr Kubrakov said on Facebook after the ships set off.
In a rare diplomatic breakthrough in the five-month war, the United Nations and Turkey have brokered a safe passage deal between Moscow and Kyiv, after the UN warned of famines due to Ukrainian grain shipments being halted.
Russian President Vladimir Putin sent troops into Ukraine on February 24, sparking the biggest conflict in Europe since World War II and causing a global energy and food crisis.
Ukraine and Russia produce about one third of global wheat, while Russia is Europe's main energy supplier.
On Friday, two grain ships set off from Chornomorsk and one from Odessa, with a total of about 58,000 tonnes of corn.
The Turkish Defence Ministry said on Twitter the Panama-flagged Navistar, carrying 33,000 tonnes of corn bound for Ireland, departed from Odessa.
The Maltese-flagged Rojen, carrying 13,000 tonnes of corn, departed from Chornomorsk bound for Britain.
The Turkish-flagged ship Polarnet, carrying 12,000 tonnes of corn, set off from Chornomorsk for the Turkish Black Sea port of Karasu.
The Turkish bulk carrier Osprey S, flying the flag of Liberia, was expected to arrive in Chornomorsk on Friday, the regional administration of Odessa said. It will be the first ship to arrive at a Ukrainian port during the war.
Ukraine has called for the grain deal to be extended to include other products, such as metals, the Financial Times reported.
"This agreement is about logistics, about the movement of vessels through the Black Sea," Ukraine's Deputy Economy Minister Taras Kachka told the newspaper.
"What's the difference between grain and iron ore?".
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 Ukraine 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, seeing it as a buffer zone against Russian-backed forces who control the city of Donetsk about 10km 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 coalmine regarded as an important defensive position.
The Russian defence ministry confirmed its offensive.
Reuters could not immediately verify either side's assertions.
On Friday, Ukraine's General Staff said Russian shelling of scores of towns across the country again targeted civilian settlements as well as military infrastructure. Russia denies targeting civilians.
Human rights group Amnesty International on Thursday said Ukraine was endangering civilians by basing troops in residential areas.
Zelenskiy hit back saying the group was trying to "shift responsibility from the aggressor to the victim".
The White House said it expected Russian officials to try and frame Ukrainian forces for an attack on the frontline 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 would launch a fact-finding mission after both sides requested an investigation.
Australian Associated Press
