Three more ships with grain have left Ukrainian ports and are headed to Turkey for inspection, Turkey's defense ministry said Friday, evidence that a U.N.-backed deal is working to export Ukrainian grain that has been trapped by Russia's invasion.

The three ships are loaded with over 58,000 tons of corn. Much of the grain that Ukraine exports is used as animal feed, experts say.

Ukraine is one of the world’s main breadbaskets and the stocks of grain trapped were exacerbating a sharp rise of food prices and raising fears of a global hunger crisis.

The departure of the ships comes after the first grain shipment since the start of the war left Ukraine earlier this week. It crossed the Black Sea under the breakthrough wartime deal and passed inspection Wednesday in Istanbul and then headed on to Lebanon.

The ships that departed Friday from Ukraine are from among over a dozen bulk carriers and cargo ships that had been loaded with grain and stuck at the ports there since the start of Russia's invasion in late February.

While tens of thousands of tons of grains are now making their way out with these latest shipments, it’s still a fraction of the 20 million tons of grains which Ukraine says are trapped in the country’s silos and ports, and which must be shipped out in order to make space for this year's harvest.

Around 6 million tons of that trapped grain is wheat, and just half of that is for human consumption, said David Laborde, an expert on agriculture and trade at the International Food Policy Research Institute in Washington D.C.

Read: Ukrainian president observes 1st grain exports leaving

Prices of grains peaked in the first weeks after Russia’s invasion, but some have since come down to their pre-war levels. Corn prices are running around 70% above the levels seen at the end of February 2020, before the pandemic, according to Jonathan Haines, senior analyst and data and analytics firm, Gro Intelligence. He said wheat prices are currently 63% above the levels seen at the end of February this year, when the invasion was launched.

The three ships that left Ukrainian ports are the Turkish-flagged Polarnet, carrying 12,000 tons of corn, which left the Chornomorsk port bound for Karasu, Turkey. The Panama-flagged Navi Star left Odesa'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, according to the United Nations.

The U.N. said the joint coordination center overseeing the deal had authorized the three ships as the operation expands, and also inspected a ship headed for Ukraine.

The Barbados-flagged Fulmar S was inspected in Istanbul and is destined for Ukraine's Chornomorsk port.

Officials from Ukraine, Russia, Turkey and the U.N. make up the Joint Coordination Center that oversees the deal signed in Istanbul last month.

The deal's aim is to create safe Black Sea shipping corridors to export Ukraine’s desperately needed agricultural products. Checks on ships by inspectors 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 U.N. said that the humanitarian corridor had to be revised after this week's first shipment “to allow for more efficient passage of ships while maintaining safety.”