Three more ships loaded with thousands of tons of grain departed Ukrainian ports on Friday, authorities said, in the latest sign that the recently concluded safe passage deal is materializing.

The ships bound for Turkey, Ireland and the United Kingdom follow the first grain shipment to pass through the Black Sea since the start of Russia’s invasion of Ukraine. The passage of that vessel heading for Lebanon earlier this week was the first under the breakthrough deal brokered by Turkey and the United Nations with Russia and Ukraine.

The Black Sea region is dubbed the world’s breadbasket, with Ukraine and Russia key global suppliers of wheat, corn, barley and sunflower oil that millions of impoverished people in Africa, the Middle East and parts of Asia rely on for survival.

The first vessels to leave are among more than a dozen bulk carriers and cargo ships that had been loaded with grain but stuck in ports since the war started in late February.

"We expect that the security guarantees of our partners from the U.N. 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 corridor deal between Moscow and Kyiv, after the U.N. warned of famines due to Ukrainian grain shipments being halted.

Russian President Vladimir Putin sent troops into Ukraine on Feb. 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 and 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 tons of corn. That is still a fraction of the 20 million tons of grains that Ukraine says are trapped in the country’s silos and ports and that must be shipped out to make space for this year's harvest.

The three ships that departed Ukraine on Friday give hope that exports will ramp up to developing nations, where many are facing the increased threat of food shortages and hunger.

Russia said on Friday it might not reach its expected harvest of 130 million tons of grain due to weather factors and a lack of spare parts for foreign-made equipment.

Ukraine’s grain exports were down 48.6% year-over-year at 1.23 million tons so far this season, its agriculture ministry said.

The Turkish-flagged Polarnet, carrying 12,000 tons of corn, left the Chornomorsk port destined for Karasu in northwestern Turkey. The Panama-flagged Navi Star left Odessa’s port for Ireland with 33,000 tons of corn. The Maltese-flagged Rojen left Chornomorsk for the United Kingdom carrying over 13,000 tons of corn, the U.N. said.

"The movement of three additional vessels overnight is a very positive sign and will continue to build confidence that we’re moving in the right direction," said Jonathan Haines, senior analyst at data and analytics firm Gro Intelligence.

"If the flow of grain from Ukraine continues to expand, it will help relieve global supply constraints."

The U.N. said that the Joint Coordination Center – run by officials from Ukraine, Russia, Turkey and the U.N. overseeing the deal signed in Istanbul last month – authorized the three ships and inspected a ship headed for Ukraine.

The empty Barbados-flagged Fulmar S was inspected in Istanbul and was headed for the Chornomorsk port to collect grain. It marks the first inbound cargo vessel since Russia’s invasion.

The checks seek to ensure that outbound cargo ships carry only grain, fertilizer or food and not any other commodities and that inbound ships are not carrying weapons. The vessels are accompanied by Ukrainian pilot ships for safe passage because of explosive mines strewn in the Black Sea.

Grain prices peaked after Russia’s invasion, and while some have since come down to their pre-war levels, they are still higher than before the COVID-19 pandemic.

Corn prices are 70% higher than at the end of February 2020, said Jonathan Haines, senior analyst at data and analytics firm Gro Intelligence. He said wheat prices are around 60% higher than in February 2020.

One reason prices remain high is the impact of drought on harvests in North America, China and other regions, as well as the higher price of fertilizer needed for farming.

"When fertilizer prices are high, farmers may use less fertilizer. And when they use less fertilizer, they will produce less. And if they will produce less, supply will continue to remain insufficient," said David Laborde, an expert on agriculture and trade at the International Food Policy Research Institute in Washington.

After Turkey, which has relations with both Russia and Ukraine, helped broker the food deal two weeks ago, President Recep Tayyip Erdoğan was to meet Russian President Vladimir Putin later Friday in Sochi, Russia.

That meeting follows another face-to-face meeting the two leaders had in Iran three weeks ago.

Separately, 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?"

The Kremlin said a solution can only be found if linked to lifting restrictions on Russian metal producers.