Turkey's military deactivated a mine on Saturday that had drifted in from the Black Sea, setting off a loud explosion north of Istanbul, days after Russia warned several of them had washed away from Ukrainian ports.
Defence Minister Hulusi Akar described the object, first discovered by fishermen in the upper Bosphorus strait, as an old type of mine and said he was in touch with both Russian and Ukrainian authorities about it.
A Reuters witness heard a loud bang off the coastal village of Rumelifeneri, where naval vessels and military planes and helicopters were active. A minehunter ship was also headed to the area from Istanbul, according to a second Reuters witness.
"The mine, determined to be an old type, was neutralized by our team...and naval forces continue their vigilant work," Akar said in a televised statement.
Earlier, the coast guard had warned vessels to stay away from the round object bobbing on the waves, and a dive team initially moved in to investigate.
Turkey shares Black Sea borders with Russia and Ukraine, which Moscow invaded last month.
Russia's main intelligence agency said on Monday that several mines had drifted out to sea after breaking off from cables near Ukrainian ports, a claim dismissed by Kyiv as disinformation and an attempt to close off parts of the sea.
The Black Sea is a major shipping artery for grain, oil and oil products. It is connected to the Marmara and then Mediterranean seas via the Bosphorus, which runs through the heart of Istanbul, Turkey's largest city with 16 million residents.
Fishermen first spotted the object near a docking area and reported it to the coast guard, which sent radio warnings to vessels in the area, the Directorate General of Coastal Safety told Reuters.
(This story refiles to correct spelling of Hulusi)
(Additional reporting by Umit Ozdal and Jonathan Spicer; Writing by Jonathan Spicer; Editing by Barbara Lewis and Christina Fincher)