Meanwhile, the north-south movement was suspended until 8:40 a.m., the coast guard said, without elaborating on the reason.
At the same time, the passage through the Dardanelles was restricted to ships with a speed of less than 10 knots due to stormy weather, the coast guard said.
Later in the day, a coast guard source told Sputnik that transit was restricted in both directions due to a breakdown on an oil tanker traveling from Russia.
"The Peria tanker, which was on its way from Russia to Izmir, lost its anchor while passing through the Bosphorus near the village of Kecilik Koyu, causing the transit of ships through the strait to be temporarily suspended in both directions," the source said.
Coast guard tugs eventually towed the Liberian-flagged vessel to a nearby pier, unblocking the shipping in the crucial waterway, which connects the Black Sea to the Sea of Marmara and via the Dardanelles to the Mediterranean.
"The Peria vessel has been tugged to a pier in Kucukcekmece, in Istanbul," a source in the Coast Guard told Sputnik.
Northward sailing in the Bosphorus resumed at 8 p.m. local time after almost 14 hours of interruption, the source added.