Russian missiles hit Ukraine's southern port of Odesa on Saturday, the Ukrainian military said, threatening a deal signed just the day before to unblock grain exports from Black Sea ports and ease global food shortages caused by the war.

Ukrainian President Volodymyr Zelenskiy said the strike showed Moscow could not be trusted to implement the deal. However, public broadcaster Suspilne quoted the Ukrainian military as saying the missiles had not caused significant damage and a government minister said preparations continued to restart grain exports from the country's Black Sea ports.

The deal signed on Friday by Moscow and Kyiv and mediated by the United Nations and Turkey was hailed as a breakthrough after nearly five months of punishing fighting since Russia invaded its neighbour. It is seen as crucial to curbing soaring global food prices by allowing grain exports to be shipped from Black Sea ports including Odessa.

A. officials had said on Friday they hoped the agreement would be operational in a few weeks and the strike on Odessa drew strong condemnation from Kyiv, the United Nations and the United States.