The last ship departed a Ukrainian port on Wednesday under a deal permitting safe Black Sea grain shipments from Ukraine, a day before Russia may pull out due to impediments to its grain and fertilizer exports.

According to UN statistics, the DSM Capella left the port of Chornomorsk carrying 30,000 tonnes of grain and was on its route to Turkey.

The United Nations and Turkey signed the Black Sea accord in July last year for an initial 120-day period to assist combat a worldwide food crisis exacerbated by Moscow’s invasion of Ukraine, one of the world’s biggest grain producers.

Moscow agreed to extend the Black Sea pact for a further 120 days in November, but then in March it agreed to a 60 day extension – until May 18 – unless a list of demands regarding its own agricultural exports was met.

To convince Russia in July to allow Black Sea grain exports, the United Nations agreed at the same time to help Moscow with its own agricultural shipments for three years.

“There are still a lot of open questions regarding our part of the deal. Now a decision will have to be taken,” Kremlin spokesman Dmitry Peskov told reporters on Tuesday, according to Russian media.

Senior officials from Russia, Ukraine, Turkey and the U.N. met in Istanbul last week to discuss the Black Sea pact. U.N. spokesman Stephane Dujarric said on Tuesday: “Contacts are going on at different levels. We’re obviously in a delicate stage.”

Turkish Foreign Minister Mevlut Cavusoglu said last week he thought the deal could be extended for at least two more months.

While Russian exports of food and fertilizer are not subject to Western sanctions imposed following the February 2022 invasion of Ukraine, Moscow says restrictions on payments, logistics and insurance have amounted to a barrier to shipments.

The United States has rejected Russia’s complaints. U.S. Ambassador to the U.N. Linda Thomas-Greenfield said last week: “It is exporting grain and fertilizer at the same levels, if not higher, than before the full scale invasion.”