Two empty oil tankers were struck by explosions in the Black Sea over a 24-hour period, with one vessel being hit twice by unmanned sea vehicles, according to the Turkish transport ministry.

The incidents, which caused damage but no casualties, have raised concerns over maritime security in the key waterway.

The series of attacks began on Friday. The ministry first reported that two vessels, the Virat and the Kairos, had experienced explosions. While no cause was initially confirmed, suspicion quickly fell on drone attacks.

The first official confirmation came on Saturday, when the ministry announced on social media platform X that the Virat had been attacked again in the early morning hours.

"The Virat, which was previously said to have been attacked by unmanned maritime vehicles approximately 35 nautical miles off the Black Sea coastline, was attacked again by unmanned maritime vehicles early this morning," the ministry stated.

It confirmed the tanker sustained only "minor damage" on its starboard side and that all 20 crew members were safe.

The attacks on the two tankers occurred hours apart in different locations.

The Kairos was the first to be struck around 1500 GMT on Friday. The Turkish maritime affairs directorate reported the vessel suffered an "external impact causing a fire" about 28 nautical miles off the Turkish coast. The Kairos was en route to the Russian port of Novorossiysk at the time. Dramatic images released by officials showed flames and thick black smoke pouring from the ship, with the fire continuing to rage for hours. All 25 crew members were safely evacuated.

The Virat was targeted later on Friday and then again on Saturday. At the time of the initial strike, it was located approximately 400 kilometres east of the Kairos incident, according to the VesselFinder tracking site. After the second attack, the ministry reported "heavy smoke detected in the engine room," though the crew did not request evacuation.

In initial comments, Turkish Transport Minister Abdulkadir Uraloglu said the explosions could have been caused by a mine, a rocket, or a drone.

"An external impact means the vessel was hit by a mine, a rocket, or a similar projectile, or perhaps by a drone, or by an unmanned underwater vehicle. These are the first things that come to mind," he told the Turkish private television channel NTV.

Adding a geopolitical dimension to the incident, both the Virat and the Kairos are subject to Western sanctions. According to VesselFinder, the tankers fly the Gambian flag and have been penalized for transporting oil from Russian ports in defiance of an embargo imposed after Russia's 2022 invasion of Ukraine.

The Black Sea has been a volatile security environment since the start of the war in Ukraine. Both sides have deployed sea mines to protect their coastlines. While many mines have been located and destroyed, others have broken free and drifted due to storms, creating a persistent hazard for commercial shipping.

In response to this threat, the NATO members bordering the Black Sea—Türkiye, Bulgaria, and Romania—established the Mine Countermeasures Naval Group (MCM Black Sea) earlier this year to coordinate de-mining operations.

Authorities are continuing their investigation into the attacks, which highlight the ongoing risks to shipping in the region. (ILKHA)