Russia's FSB security service said Thursday it had found "traces of explosives" on a cargo ship bound for the Russian port of Rostov-on-Don through the Black Sea.
The FSB said that the ship coming from Türkiye had previously sailed to the Ukrainian port of Reni and said it had now been turned back from Russian waters.
"The foreign ship may have been used earlier to transport explosive substances to Ukraine," the FSB statement said.
"A decision was taken to prevent the ship's passage under the shipping arch of the Kerch Strait and it has been turned back from Russian territorial waters," it added.
Reni is located on the Danube near the Romanian border and a grain storage facility there was targeted by a Russian drone attack in recent days.
Russia has stepped up strikes against port facilities in southwest Ukraine after withdrawing from a deal to allow Ukrainian grain exports through the Black Sea.
This is the second such incident reported by the FSB.
On Monday, it said that traces of explosives had been found on a ship sailing from Türkiye to Rostov-on-Don which had previously been to the Ukrainian port of Kiliya and it too was turned back.
