Ukraine has asked Turkey to close the Bosphorus and Dardanelles straits to Russian ships and wants sanctions imposed on Moscow, Ukraine's ambassador to Ankara said on Thursday, after Russia launched air and ground assaults on its neighbor.

NATO member Turkey Ukraine, which shares a maritime Black Sea border with Ukraine and Russia, opposes sanctions but has called Russian steps against Ukraine unacceptable, while offering to mediate. Under a 1936 pact, Ankara has control over the straits and can limit warship passages if it is threatened or during wartime.

"We are calling for the air space, Bosphorus and Dardanelles straits to be closed. We have conveyed our relevant demand to the Turkish side. At the same time, we want sanctions imposed on the Russian side," Ambassador Vasyl Bodnar told a news conference in Ankara.

On Wednesday, Bodnar had told Reuters that Kyiv viewed the presence of Russian warships in the Black Sea coasts near Ukraine as a threat, and that Ukraine would ask Ankara to consider shutting its two straits to Russian ships if Moscow invades.

Earlier this month, six Russian warships and a submarine transited the Dardanelles and Bosphorus straits to the Black Sea for what Moscow called naval drills near Ukraine waters.

Asked about the presence of Russian warships near Ukrainian borders, Bodnar told Reuters in an interview that the vessels posed "a great danger" for Kyiv, adding the Russian naval concentration in the Black Sea was "overwhelming".

"We believe that, in case of a wide military invasion or the starting of military activities against Ukraine - when the war becomes not only de facto but de jure - we will ask the Turkish government to consider the possibility of closing the Black Sea straits for the aggressor state," he had said.

Under the 1936 Montreux Convention, NATO member Turkey has control over the Bosphorus and Dardanelles straits, linking the Mediterranean and Black seas. The pact gives Ankara the power to regulate the transit of naval warships and to close the straits to foreign warships during wartime and when it is threatened.

President Recep Tayyip Erdoğan said Wednesday that Turkey, which has good ties with both Ukraine and Russia, could not abandon its ties with either country and that it would take steps to ensure relations remain intact.

"It is not possible for us to abandon either (country)," he said and called on both Ukraine and Russia to resume negotiations, while urging NATO to "determine its stance" and "do whatever it will" after a summit on Wednesday.

"Our aim is that we take such a step that, God willing, we sort this out without abandoning either one."

While building close cooperation with Russia on defense and energy, Ankara has also sold sophisticated drones to Ukraine and signed a deal to co-produce more, angering Moscow.

Turkey opposes Russian policies in Syria and Libya, its annexation of Crimea in 2014 and its 2008 recognition of two Georgian regions.

Erdoğan also told his Russian counterpart Vladimir Putin on Wednesday that Turkey did not recognize steps against Ukraine's territorial integrity, after Russia recognized two breakaway regions in eastern Ukraine.

In a call, Erdoğan told Putin that military conflict in the region would not benefit anyone and repeated his offer to help solve the crisis, his office said in a statement, adding Erdoğan said he valued Putin's close cooperation on regional issues and wanted to continue this.

"President Erdoğan, who renewed his call for the matter to be resolved through dialogue, stated that it was important to bring diplomacy to the forefront, and that (Turkey) continued its constructive stance in NATO as well."

Putin expressed disappointment to Erdoğan at what he said were attempts by Washington and NATO to ignore Russia's security demands, Interfax cited the Kremlin as saying.

More about: #Ukraine