Russia said that a landmark deal to ensure the safe export of grain from Ukraine’s Black Sea ports was only being “half-implemented”, raising doubts as to whether Russia would allow an extension of the agreement due to expire next week.

The Black Sea Grain Initiative, brokered by the United Nations and Turkey last July, aimed to prevent a global food crisis by allowing Ukrainian grain blockaded by Russia’s invasion to be safely exported from three Ukrainian ports. The deal was extended for 120 days in November and will renew on March 18 if no party objects. However, Moscow has already signaled it will only agree to an extension if restrictions affecting its own exports are lifted.

Russia’s agricultural exports have not been explicitly targeted by the West, but Moscow says sanctions on its payments, logistics, and insurance industries are a barrier to its being able to export its own grains and fertilizers.

“There are still a lot of questions about the final recipients, questions about where most of the grain is going. And of course, questions about the second part of the agreements are well known to all,” Kremlin spokesman Dmitry Peskov said.

Russia also complained that Ukrainian grain exported under the deal is going to wealthy countries.

Andriy Yermak, the Ukrainian President’s chief of staff, said the grain deal was part of the country’s plan to end the war and should be extended indefinitely. Quoted by Interfax Ukraine news agency, he said any suggestion of ending the grain initiative amounted to “pressure on its intermediaries – Turkey and the U.N.”

He added that “at the very least, the deal has to be extended by the same term as before”.

Ukrainian President Volodymyr Zelenskyy and U.N. Secretary-General Antonio Guterres held talks on Wednesday on extending the deal, which Guterres said was of “critical importance”.

“Exports of Ukrainian – as well as Russian – food and fertilizers are essential to global food security and food prices,” Guterres added.

Top U.N. trade official Rebeca Grynspan is set to discuss the grain deal with senior Russian officials in Geneva next week.

Ukraine has so far exported more than 23 million tonnes of mainly corn and wheat under the initiative. The top primary destinations for shipments have been China, Spain, Turkey, Italy, and the Netherlands.