Turkey seeks to persuade Russia to rejoin the agreement, which allowed Ukraine to export farm goods across the Black Sea.

Monday’s meeting came nearly two months after Russia quit a UN- and Turkey-brokered agreement that allowed Ukraine to export grain and other commodities from three of its Black Sea ports during the war with Russia.

“Everyone is looking at the grain corridor issue,” Erdogan said in his opening remarks.

Welcoming Erdogan to Russia, Putin said: “We are open to negotiations on this question.”

Reporting from Sochi, Al Jazeera’s Dorsa Jabbari said the head of the central banks of Turkey and Russia would also be discussing the Black Sea grain export deal on the sidelines of the summit to sort out payment methods.

Putin and Erdogan “have been friends for a long time, and this meeting is a critical point for both to reach an agreement, especially on the grain deal, which affects world food supplies”, she added.

Analysts expect tough negotiations in Sochi.

“My gut feeling is that Putin recognises the leverage he has by using food as an economic weapon and thus will fight for all he can get in terms of concessions on his wish list,” said Tim Benton, a food security expert at the Chatham House think tank.

Those may include Russia’s own grain, fertiliser exports or wider issues, he said.

The abandoned deal was aimed at alleviating a global food crisis by allowing grain from Ukraine to leave ports while the conflict is going on.

Russia and Ukraine are two of the world’s biggest agricultural producers and key players in the wheat, barley, corn, rapeseed, rapeseed oil, sunflower seed and sunflower oil markets.

Putin has previously said Russia could return to the grain agreement if the West fulfils a separate deal to facilitate Russian food and fertiliser exports, which still face obstacles.

UN Secretary-General Antonio Guterres said last week that he had sent Russian Foreign Minister Sergey Lavrov “a set of concrete proposals” to revive the deal.

But Russian Ministry of Foreign Affairs spokesperson Maria Zakharova said on Saturday that Russian demands implied by the agreement had yet to be implemented under the previous deal. She did not give details.

Since quitting the grain deal in July, Russia has targeted Ukrainian ports with missile and drone strikes and threatened to treat all vessels on the Black Sea as potential military targets.

Ukraine has announced a “humanitarian corridor” as an alternate route. It hugs the coast of neighbouring Romania and Bulgaria.