Ukraine has around $10 billion worth of grain available for sale in the wake of a deal signed with Russia to unblock supplies and will also have a chance to sell the current harvest, President Volodymyr Zelenskiy said on Friday.

"This is another demonstration that Ukraine can withstand the war," he said in a late-night address.

Russia and Ukraine signed a landmark deal on Friday to reopen Ukrainian Black Sea ports for grain exports, raising hopes that an international food crisis aggravated by the Russian invasion can be eased.

"Approximately 20 million tons of last year's grain harvest will be exported. There will also be a chance to sell this year's harvest ... at the moment we have about $10 billion worth of grains available," said Zelenskiy.

The deal, brokered by the United Nations and Turkey, was a chance to prevent a global food catastrophe that could cause chaos in many countries, he said.

"There may be some provocations on the part of Russia, attempts to discredit Ukrainian and international efforts," said Zelenskiy. "But we trust the United Nations."

(Reporting by David Ljunggren; Editing by Leslie Adler and Alistair Bell)