An agreement to facilitate Ukrainian grain exports via the Black Sea is due to be signed by UN Secretary General António Guterres, Turkish President Recep Tayyip Erdoğan and representatives of Russia and Ukraine on Friday, according to Erdoğan’s office. The deal provides for the creation of a United Nations-run control centre in Istanbul to oversee grain exports that will be staffed by representatives of Russia, Ukraine and Turkey. The parties have reportedly agreed that ships bound for Ukraine will first be searched to ensure no weapons or other military equipment are on board. Searches are a…