STORY: "This is very much felt in combat, especially in the Donbas. … It is just hell there. Words cannot describe it," he said in his nightly video address.

A July 22 U.N.-brokered deal to unblock the export of Ukrainian grain had an initial success - Turkey said that the first loaded ship since Russia's invasion more than five months ago was safely anchored off the Turkish coast on Tuesday.

Zelenskiy welcomed this development in his address, saying: "Our goal now is to have an orderly schedule so when one ship leaves port there should be other vessels."

Known as Europe's breadbasket, Ukraine hopes to export 20 million tonnes of grain held in silos and 40 million tonnes from the harvest now under way, initially from Odessa and nearby Pivdennyi and Chornomorsk, to help clear silos for the new crop.

Russia and Ukraine accuse each other of laying mines that now float around the Black Sea and represent a hazard to shipping.