A Russian attack submarine operating in the Mediterranean has reportedly suffered a “serious accident,” raising concerns of a potential explosion.

The vessel, identified as the 242-foot Kilo-class submarine Novorossiysk, is said to be leaking fuel, which experts warn could create a dangerous “explosive hazard.”

The submarine is part of Russia’s Black Sea Fleet and is capable of carrying nuclear weapons, though it remains unclear if any were onboard at the time of the incident. No official confirmation has yet been provided by the Russian Ministry of Defense.

Military analysts caution that the situation could escalate quickly if the damage is not contained, both due to the risk of detonation and the environmental threat posed by leaking fuel.

The reported accident comes amid heightened tensions between Russia and NATO in the region, where naval activity has increased significantly over the past year.