Moscow has denied carrying out any attack on the Ukrainian port of Odessa, the Turkish defence minister said Saturday, a day after Moscow and Kyiv penned a deal to resume grain exports.

"The Russians told us that they had absolutely nothing to do with this attack and they were looking into the issue very closely," Hulusi Akar said, but Russia has yet to officially comment.

Russia and Ukraine signed agreements in Istanbul on Friday brokered by Turkish President Recep Tayyip Erdogan and UN chief Antonio Guterres.

But Akar also said the incident "really makes us concerned" in comments to state news agency Anadolu.

"We will continue to fulfil our responsibilities under the agreement we reached yesterday," he added.

Up to 25 million tonnes of wheat and other grain have been blocked in Ukrainian ports by Russian warships and landmines Kyiv has laid to avert a feared amphibious assault.

rba/raz/ah