NATO members Turkey, Bulgaria and Romania on Thursday signed an agreement on demining the Black Sea to ensure safe waters after Russia's war in Ukraine.

The Russian navy mined Ukraine's Black Sea coastline in the early stages of its invasion nearly two years ago.

Some of the mines have since washed up in the waters of the three countries, endangering shipping and complicating Ukraine's efforts to break through a Russian naval blockade.

Top defence officials from Turkey, Bulgaria and Romania signed a memorandum of understanding in Istanbul establishing the Mine Countermeasures Naval Group in the Black Sea (MCM Black Sea), which will oversee demining operations.

"It is of vital importance to be protected from security risks that war could cause," Turkish Defence Minister Yasar Guler said at the signing ceremony.

"With the start of the war, mines drifting in the Black Sea posed a threat. To overcome this, we have come this far with joint efforts of our Bulgarian and Romanian allies," he added.

In December, Ukrainian authorities said a Panama-flagged ship arriving to collect grain hit a Russian naval mine in the Black Sea, injuring two sailors.

Ukraine has created a maritime corridor for commercial ships which first pass near the shores of Bulgaria and Romania.

Guler emphasised that the initiative would involve only the ships of the three Black Sea littoral states, adding that other countries' contributions would be possible when conditions are met.

Neither Russia nor Ukraine provided immediate comment.

Turkey controls Black Sea maritime and naval traffic, which must pass Istanbul's Bosphorus Strait and the Dardanelles before reaching the Aegean and Mediterranean seas.

With the outbreak of war, Turkey invoked a clause of an international treaty called the Montreux Convention banning the passage of naval vessels from non-littoral countries to and from the Black Sea.

The measure prevented Britain from following through on plans last month to send two mine hunting ships in the region to help Ukraine's efforts to export its grain.

The Turkish presidency said early this month that Ankara, which has implemented the convention since 1936, "maintains its unwavering determination and principled stance throughout this war to prevent the escalation of tension in the Black Sea."

"Our pertinent allies have been duly apprised that the mine-hunting ships donated to Ukraine by the United Kingdom will not be allowed to pass through the Turkish Straits to the Black Sea as long as the war continues," it said.

bur-fo/ach