“Odesa. Air defence combat work continues,” said Sergiy Bratchuk, spokesman for the Odessa military region, on Telegram.

The Odesa region in southern Ukraine is home to maritime terminals that were key to the expired grain export agreement between Moscow and Kyiv.

Russia was “attacking the south of Ukraine with attack drones,” head of the Odesa region’s military administration, Oleg Kiper, said on Telegram.

He warned residents to stay in shelters.

Ukraine’s southern operations command said Russia was “attacking the southern regions with unmanned attack vehicles”.

Air alerts were also announced in Mykolayiv, Kherson, Zaporizhzhia, Donetsk, Kharkiv, Dnipropetrovsk, Poltava, Kirovograd, and Cherkasy.

Russia’s invasion last year saw Ukraine’s Black Sea ports blocked by warships until the agreement, signed in July 2022, allowed for the passage of critical grain exports.

The deal expired at midnight in Istanbul after Russia refused an extension, arguing that elements of the deal allowing the export of Russian food and fertilisers had not been honoured.