Four more ships carrying almost 170,000 tonnes of corn and other foodstuffs have set sail from Ukrainian Black Sea ports under a deal to unblock the country's exports after Russia's invasion, Ukrainian and Turkish officials have said.

The United Nations and Turkey brokered the agreement last month after warnings that the halt in grain shipments caused by the conflict could lead to severe food shortages and even outbreaks of famine in parts of the world.

Ukrainian Infrastructure Minister Oleksandr Kubrakov said there were plans to step up shipments still further.

"We are gradually moving on to larger volumes of work. We plan to ensure the ability of the ports to handle at least 100vessels per month in the near future," he added.

Ukraine would soon also start exporting grain from its Black Sea port of Pivdennyi, an expansion that would let it send out a total of at least three million tonnes of goods a month, the minister said on Facebook.

Before Russia started what it calls its "special military operation", Russia and Ukraine together accounted for nearly a third of global wheat exports. In peacetime, Ukraine exported up to six million tonnes of grain from its Black and Azov sea ports every month.

The resumption of grain exports is being overseen by a Joint Coordination Centre (JCC) in Istanbul where Russian, Ukrainian, Turkish and UN personnel are working.

The first cargo ship left Ukraine under the agreement on Monday last week, and another three followed on Friday.

The JCC said late on Saturday it had authorised five new vessels to pass through the Black Sea corridor: four vessels outbound from Ukraine's Chornomorsk and Odesa ports, carrying 161,084 metric tonnes of foodstuffs, and one heading into Ukraine to pick up grain.

The vessel 'Glory' leaving Chornomorsk port

The ships that left Ukrainian ports included Glory, with a cargo of 66,000 tonnes of corn bound for Istanbul, and Riva Wind, loaded with 44,000 tonnes of corn, heading for Turkey's Iskenderun, the Turkish defence ministry said.

It said the other two vessels that left Ukraine were Star Helena, with a cargo of 45,000 tonnes of meal heading to China, and Mustafa Necati, carrying 6,000 tonnes of sunflower oil and heading for Italy.

Later on Sunday, Ukraine's Infrastructure Ministry said the bulk carrier Fulmar S, which had reached the Black Sea port of Chornomorsk on Saturday - the first foreign-flagged ship to arrive in Ukraine since the conflict - was ready for loading.

The JCC said it had nearly finished drafting procedures to implement the grain deal and they would be published in days.

It added that it had also authorized the movement, pending inspection, of Osprey S, inbound for Chornomorsk. That ship is currently at anchorage northwest of Istanbul.

The Turkish Defence Ministry said the JCC had completed inspections of the ship Rojen carrying 13,000 tonnes of corn to Britain, Polarnet which is taking 12,000 tonnes of corn to a Turkish port and Osprey S, which is heading to Ukraine.

On Saturday, the JCC completed its inspection of Navistar, the other one of three vessels that left Ukrainian ports on Friday.

The first ship to leave a Ukrainian port under the deal will not arrive in Lebanon on Sunday as planned, the Ukrainian embassy in Lebanon said.

The Razoni left Odesa on Monday carrying 26,527 tonnes of corn.

The embassy told Reuters the ship was "having a delay" and "not arriving today," with no details on a new arrival date or the cause of the delay. Refinitiv Eikon data showed the Razonioff the Turkish coast on Sunday morning.

We need your consent to load this rte-player contentWe use rte-player to manage extra content that can set cookies on your device and collect data about your activity. Please review their details and accept them to load the content.Manage Preferences

Meanwhile, in Russia, Moscow has accused Kyiv's forces of again shelling the Zaporizhzhia nuclear plant in the south of Ukraine, which it took control of shortly after invading its pro-Western neighbour.

The Ukrainian army "carried out a strike with a cluster bomb fired from a Ouragan multiple rocket launcher," the occupying authorities in Energodar, the town where the plant is situated, were quoted by the Russian state news agency TASS as saying.

"The shrapnel and the rocket engine fell 400 metres (1,300 feet) from a working reactor", "damaged" administrative buildings and hit "a used nuclear fuel storage area," the authorities said, without providing any evidence to back up the claims.

AFP was not able to confirm the allegations from an independent source.

On Saturday, the plant's operator, Energoatom, had already said that parts of the facility had been "seriously damaged" by military strikes and one of its reactors was forced to shut down.

Both Ukraine and Russia accuse each other of attacking the plant.

Because Zaporizhzhia is Europe's biggest nuclear plant, the prospect of it being seriously damaged in the fighting is setting alarm bells ringing, not least at the UN's nuclear watchdog, the International Atomic Energy Agency.

The strikes underline "the very real risk of a nuclear disaster", the IAEA's director general, Rafael Grossi, said on Saturday.

"Any military firepower directed at or from the facility would amount to playing with fire, with potentially catastrophic consequences," Mr Grossi said.

And the European Union's top diplomat Josep Borrell condemned the attack as "a serious and irresponsible breach of nuclear safety rules and another example of Russia's disregard for international norms".