Istanbul: Two oil tankers under international sanctions were damaged after explosions in the Black Sea near Turkey’s coast, prompting a large rescue response and raising new concerns about maritime safety in the region.

The tankers, Kairos and Virat, were travelling near the entrance of the Bosphorus Strait when they were hit by separate blasts during their voyage.

Authorities said both incidents appeared to be caused by an external impact, although the exact cause has not yet been confirmed. Officials have not ruled out the possibility of sea mines, which have previously been reported drifting in the Black Sea.

The explosion on the Kairos caused a fire, but all 25 crew members on board were safely taken off the vessel. The second tanker, Virat, was struck around 35 nautical miles farther offshore. Its engine room reportedly filled with smoke, but all 20 crew members were found in good condition during the rescue.

Emergency teams sent fast response boats, tugboats and specialized rescue vessels to assist both ships. Despite the incidents, shipping traffic through the Bosphorus continued without major disruption.

Both tankers are part of a group of vessels known as a shadow fleet, which are linked to trade routes affected by sanctions imposed on Russia after its invasion of Ukraine. Their presence in risky waters has increased worries about safety and environmental danger.

Authorities said the investigation into the explosions is ongoing. There have been other cases this year of ships striking mines or reporting unexplained damage in the Black Sea as regional tensions continue.

For now the two damaged tankers remain under observation as officials assess the next steps and monitor possible environmental impact.