Turkey has indicated that it may raise the fees it charges commercial ships to use the heavily congested Bosporus Strait once it finishes building a canal designed as an alternative route.
Turkey wants to reduce the shipment of oil, liquefied gas and chemicals through the Bosporus and the risk of accidents in the narrow waterway that bisects Istanbul, a city of more than 12 million people.
Prime Minister Recep Tayyip Erdogan recently announced a new canal project that would create a second waterway linking the Mediterranean Sea with the Black Sea.
The Montreux Convention of 1936 requires Turkey to allow commercial ships through the strait, dividing Europe and Asia, while restricting the passage of military ships.
But Transportation Minister Mehmet Habib Soluk said Turkey could reconsider its policy of charging discounted fees for transit through the Bosporus Strait once the canal is operational.
The plan is to complete the canal by 2023, the year Turkey will be celebrating the centenary of the founding of the Turkish republic after the fall of the Ottoman Empire.
Increasing the Bosporus fees could persuade ships to use the proposed Canal Istanbul, even though fees also are expected to be charged there to cover its construction costs.
Turkey said it has no plans to block passage through the Bosporus. But it believes the canal, which would link the Black Sea to the Sea of Marmara further west of Istanbul, would attract ships that the Prime Minister said lose about $1.4 billion annually by waiting at either end of the Bosporus for permission to cross through.
Ships coming from the Black Sea wend their way through the 31-kilometre (20-mile) Bosporus and its 12 turns, emerge in the Sea of Marmara and sail through the Dardanelles into the Mediterranean. Problems are less serious in the Dardanelles, a strait that is wider, has less treacherous currents and much less local boat traffic.
About 150 big ships transit the Bosporus each day, including up to 15 oil tankers, and many of them are Russian. They share a waterway that is generally only about 1,000 yards (meters) wide with tugs, coast guard cutters, fishing boats, cruise ships, ferries, yachts, pilot boats and water taxis.
The Bosporus, lined up with palaces, mosques and wooden mansions, has been the site of numerous accidents over the decades.