A local media reported that the first ship to use a temporary corridor to and from Ukraine’s seaports entered Turkey’s Bosporus Strait early Friday.
According to the report, the Hong Kong-flagged container ship operated by a German company reached the Bosporus at 6:10 a.m. (0310 GMT).
The ship sailed out of the Ukrainian Black Sea on Wednesday evening, many hours after departing the southern city of Odessa.
The ship had been detained there for more than a year and a half, during Russia’s full-scale invasion of Ukraine.
Merchant ships, according to Ukraine, can utilize the passage at their own risk.
Kiev established the corridor after Russia cancelled a UN-brokered accord in July to transport essential food exports out of Ukraine’s blockaded ports.
There have been safety worries because Russia considers all ships en route to Ukrainian ports to be possible transporters of supplies for the Ukrainian army.
On its way to the Danube port of Izmail on Sunday, the Russian military halted and inspected a ship owned by a Turkish firm.
After days-long silence, Turkey late on Thursday said it warned Moscow over the incident.
The Russian parties were “appropriately warned” to avoid such attempts that would “escalate tensions in the Black Sea,” the Turkish presidency said.
Turkey, along with the UN, had brokered the now frozen grain deal between Ukraine and Russia and sees itself as a mediator in the war.
President Recep Tayyip Erdoğan earlier said he expects to convince his Russian counterpart Vladimir Putin to renew the grain deal.
Moscow has not so far confirmed any such plans.