Turkish president on Friday said that he expects “positive” steps from Russia and Ukraine to resolve recent tensions between the two countries.

Speaking to reporters in Istanbul, Recep Tayyip Erdogan said: “I held a phone conversation with [Russian President] Mr. [Vladimir] Putin in this regard, held an inter-committee meeting in Argentina and I also spoke with [Ukrainian President] Mr. [Petro] Poroshenko over the phone.”

“I hope they [Russia and Ukraine] will have a positive approach,” Erdogan said, and added “I think there is an investigation going on” over the detention of Ukrainian sailors.

“We can only make a request, we cannot go further,” the president added.

During a two-day NATO foreign minister’s meeting on Wednesday, NATO Secretary-General Jens Stoltenberg reiterated his call on Russia to ensure freedom of navigation and release the Ukrainian sailors and ships that it seized “without delay”.

Russia seized two Ukrainian navy ships and a navy tugboat along with 23 crew members Sunday off Crimea, accusing Kiev of entering its waters and provoking a conflict.

It said the vessels had ignored calls to stop, sparking military action.

Russia intervened as the Ukrainian ships were relocating from the Black Sea port of Odessa to the port of Mariupol in the Sea of Azov.

Videos appeared online showing a Russian coast guard vessel ramming the Ukrainian navy tugboat in the Kerch Strait.

Ukraine also accused Russian warships of opening fire on the ships, asserting that crew members were wounded and the vessels were seized by Russia.

Russia and Ukraine have been at loggerheads since 2014, when Russia annexed Crimea after a controversial referendum.

Turkey, as well as the UN General Assembly, viewed the annexation as illegal.

Ukraine has also blamed Russia for separatist violence in eastern Ukraine near the border with Russia.