An agreement allowing Ukraine to export grain through Black Sea will continue "under current terms," a senior Turkish official told AFP.

"The agreement will remain in place under current terms for four months," the official told AFP on condition of anonymity.

Ukraine is one of the world's top grain producers, and Russia's invasion of the country blocked 20 million tonnes of grain in its ports before the United Nations and Turkey brokered the deal in July.

The official told AFP the agreement would be in force for "120 days considering the winter conditions", adding that there could be "new arrangements" after the winter season.

An international source close to the negotiations also confirmed to AFP that the parties concerned agreed to extend the deal.

On Wednesday, Turkish President Recep Tayyip Erdogan said at a press conference at the G20 summit in Indonesia: "I am of the opinion that it (the deal) will continue. There's no problem there."