Turkey on Monday called for calm between Russia and Ukraine after navy vessels clashed off Crimea, stressing the importance of free passage through the Kerch strait to the Sea of Azov.

 

The government was "concerned by reports of Ukrainian ships being fired on and some being injured," the Turkish foreign ministry said in a statement.

 

"We stress that passage should not be blocked on the Kerch strait," it said.

 

"We call for actions taken with reason and moderation to avoid escalating tensions," it said, without directly naming Russia.

 

International law should be respected, it added.

 

Russia on Sunday seized three Ukrainian navy ships in the strait, a narrow waterway connecting the Sea of Azov to the Black Sea and which is used by both Ukraine and Russia.

 

Ukraine's navy said a Russian border guard vessel rammed one of its tugboats which was accompanied by two small warships, before firing on the ships and immobilising them. 

 

Kiev said six of its 23 soldiers were injured, two seriously, but Russia's FSB reported only three had suffered non-life threatening injuries and were given medical treatment.

 

Russia, which claims the waters off Crimea after annexing the peninsula in 2014, accused Kiev of illegally entering its waters.

 

The crisis stoked fears of a military escalation, with an emergency meeting of the UN Security Council expected later on Monday.

 

As well as the annexation of Crimea, Kiev accuses Russia of backing pro-Moscow separatists who seized control of part of Ukraine's east.

 

Ankara and Moscow have been working closely over the Syrian conflict -- despite being on opposing sides of the war -- and to increase trade ties.

 

Turkish President Recep Tayyip Erdogan and Russian counterpart Vladimir Putin often speak to each other by telephone and have met frequently.

 

Although Turkey and Russia enjoy warm relations, Ukrainian President Petro Poroshenko came to Turkey twice this year. During his visit in April, Poroshenko discussed energy cooperation with Erdogan and Ankara's ally Qatar.