Turkey Defense Minister, Hulusi Akar, confirmed that Moscow has denied carrying out any attack on the Ukrainian port of Odessa, only one day after Russia and Ukraine inked 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," Akar mentioned.

On Friday, Russia and Ukraine signed agreements in Istanbul 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.

Ukraine military says air defenses shot down 2 cruise missiles

Commenting on the attack on the port of Odessa, Ukraine's President Volodymyr Zelensky accused Russia of routinely violating agreements.

"This proves only one thing: no matter what Russia says and promises, it will find ways not to implement it," Zelensky claimed during a meeting with US lawmakers, according to a statement from the Ukrainian presidency.

The Ukrainian military claimed that its air defenses shot down two cruise missiles but two others hit the port.

Guterres - who presided over the signing ceremony on Friday - "unequivocally" condemned the reported attack on Odessa, his deputy spokesperson said, and urged all sides to stick to the deal to allow grain exports.

"These products are desperately needed to address the global food crisis and ease the suffering of millions of people in need around the globe," he pointed out.

The EU's foreign policy chief Josep Borrell directly and instantly accused Russia of the strikes without any investigation.

"Striking a target crucial for grain export a day after the signature of (the) Istanbul agreements is particularly reprehensible and again demonstrates Russia's total disregard for international law and commitments," Borell claimed.

20 million tonnes of wheat

The first major accord between the countries since the start of the war in Ukraine aims to ease the "acute hunger" that the United Nations says an additional 47 million people faces because of the war.

The two sides inked separate but identical agreements in the presence of Guterres and Erdogan at Istanbul's lavish Dolmabahce Palace.

Guterres, moments before the signing, hailed the agreement as "a beacon of hope."

Ukrainian President Volodymyr Zelensky later said the responsibility for enforcing the deal would fall to the United Nations, which along with Turkey is a co-guarantor of the agreement.

The agreement includes points on running Ukrainian grain ships along safe corridors that avoid known mines in the Black Sea.

Zelensky said that around 20 million tons of produce from last year's harvest and the current crop would be exported under the agreement, estimating the value of Ukraine's grain stocks at around $10 billion.

Russian Defence Minister Sergei Shoigu told Kremlin state media that he expected the deal to start working "in the next few days."