Russian President Vladimir Putin has warned that he could scrap a grain exports deal with Ukraine.

The agreement was brokered by the United Nations and Turkey last July to allow Ukraine to resume agricultural exports by sea.

It has been extended three times, but could expire on Monday.

On Thursday, Putin expressed discontent about the deal, saying nothing has been implemented that benefits Russia. He went on to say that blocking another extension is an option.

On Friday, Turkish President Recep Tayyip Erdogan told reporters that he and Putin agree that the deal should be extended.

UN Secretary-General Antonio Guterres wrote a letter to the Russian leader expressing his wish for another extension. Putin is yet to respond.

Moscow's Presidential spokesperson Dmitry Peskov indicated on Friday that Russia is still in deliberations over the deal.