Ukraine's ambassador to Turkey has made an official request to Ankara to close two of its waterways in the Black Sea and its airspace to Russian forces on Thursday, as Moscow troops invade the Eastern European country.
"We conveyed our official request to the Turkish side regarding the closure of the airspace, the Dardanelles [Strait] and Bosphorus [Strait] for Russian ships," Ambassador Vasyl Bodnar told reporters at a press conference, according to the Turkish daily Hurriyet.
Bodnar also called for Ankara to impose sanctions on Russian businessmen, and stressed the importance of humanitarian and financial assistance.
"We also call for support to the citizens of Ukraine currently in Turkey, especially those who need additional protection and security", he added.
He also called for the international community to "form a coalition" against Russian President Vladimir Putin, who announced an invasion of Ukraine on Thursday morning.
Bodnar voiced his concerns on Wednesday that Russian warships posed a "great danger" for Kyiv and said that the Russian naval concentration in the Black Sea is "overwhelming", in an interview with Reuters.
Under the 1936 Montreux Convention regarding control of the straits, Turkey has control over the Bosphorus and Dardanelles, which link the Mediterranean and Black seas.
The treaty grants Ankara the authority to monitor the transit of naval warships and to close the straits to foreign warships during wartime.
President Recep Tayyip Erdogan told President Vladimir Putin on Wednesday that Ankara would not recognise any move against Ukraine's sovereignty, and warned against a military conflict.
However, he said that Turkey could not abandon its ties with either country, and has offered to mediate between them, according to the broadcaster NTV.
Turkey has expressed opposition towards Russia's annexation of Crimea in 2014 and its 2008 recognition of the two Georgian regions of Abkhazia and South Ossetia.