UN Secretary-General Antonio Guterres is on his way to Kiev for a meeting with President Volodymyr Zelenskyy. They will discuss the extension of an agreement on Ukrainian farm exports that is set to expire next week.

The UN says Guterres arrived in Poland on Tuesday. He will meet with Zelenskyy in Kyiv on Wednesday.

This will be the secretary-general's third visit to Ukraine since the start of Russia's invasion in February last year.

UN officials say Guterres and Zelenskyy will discuss the Black Sea Grain Initiative, an agreement to facilitate exports of Ukrainian agricultural products that is set to expire on March 18.

The agreement between Ukraine and Russia was mediated by the United Nations and Turkey last year. It allowed shipments from Black Sea ports, which have been blocked by Russian forces, to resume.

Russia has suggested that it may not agree to an extension.

The deputy spokesperson for the UN secretary-general, Farhan Haq, told reporters on Tuesday that, "There is no visit to Moscow planned."

Haq said Guterres had spoken to Russian Deputy Foreign Minister Sergey Vershinin on the phone before leaving New York.

He added that a Russian delegation will be in Geneva next week for further discussions on the Black Sea Grain Initiative.