MOSCOW: A Russian official said a landmark deal allowing Ukraine to export grain through its Black Sea ports has been extended for 60 days, though Kyiv said it would stick to a 120-day extension and Turkey said talks were ongoing.

Since Russia and Ukraine signed the U.N.-backed Black Sea Grain Initiative in Turkey on July 22, millions of tonnes of grain and other food products have been exported from Ukrainian ports.

Russia on Monday suggested allowing the deal to be renewed, but for half the term of the previous renewal, while the United Nations pledged to do everything possible to ensure the agreement's integrity remained intact.

"Indeed, the deal has been extended - it has been agreed that it has been extended for 60 days," the TASS news agency cited Russia's Deputy Foreign Minister Alexander Grushko as saying on Tuesday.

RIA news agency also quoted Grushko as saying the deal had been extended. According to RIA, Grushko cited another deputy foreign minister, Sergei Vershinin, confirming the extension.

United Nations officials gave no immediate comment on the extension.

It was not immediately clear how the deal could be extended for half of the previous renewal. Turkey said talks continued, while Ukraine said it will stick to the terms of the previously agreed deal.

"We will follow the agreement strictly," a senior Ukrainian government official told Reuters. The official declined to be identified.

In a statement that said talks were ongoing, the Turkish defence ministry cited Russia as agreeing to back a 60-day extension to the deal, brokered between Moscow and Kyiv in July by Turkey and the United Nations.

Russia has said that, although the West has not explicitly targeted the country's agricultural exports, sanctions on its payments, logistics and insurance industries have created a barrier to the export of its grains and fertilisers.