A Russian tanker carrying more than 4,000 tons of oil products has sunk in stormy conditions in the Black Sea, while a second has run aground, threatening an ecological disaster.

The cargo ship Volgoneft-212 broke in half on Sunday after being hit by a large wave. A video showed the bow end sticking vertically out of the water. The boat ran into trouble off the east coast of occupied Crimea, 5 miles (8 km) from the Kerch Strait, Russian media reported.

Russian investigators opened two criminal cases to investigate possible safety violations after at least one person was killed when the 136-meter-long tanker sank with 15 people on board.

The tanker was carrying 4,300 tons of low-grade heavy fuel oil known as mazut. The Russian rescue service launched a rescue operation using tugboats and a Mil-Mi-8 helicopter. Twelve more people were evacuated, 11 of them were taken to hospital, two of whom were in serious condition, Tass news agency quoted Alexei Kuznetsov, an adviser to the health minister, as saying.

Shortly afterwards, another cargo transporter, the Volgoneft-239, ran into difficulties in the same area. It carried 4 tons of fuel oil. Initial reports also suggested that the ship had sunk. “Another ship is sinking. Holy shit!” said a sailor filming from a nearby boat.

However, the Emergencies Ministry said the 132-meter-long ship, built in 1973, ran aground 80 meters offshore near the port of Taman at the southern end of the Kerch Strait.

The ministry later wrote on Telegram that efforts to evacuate the 14-member crew had been suspended due to bad weather. The ministry said rescue teams were in contact with the ship, which had all the necessary facilities on board to ensure the crew’s lives were not in danger.

Officials did not provide any information about the extent of the spill or the reasons why the first tanker suffered such severe damage.

President Vladimir Putin has ordered the government to set up a working group to deal with the rescue operation and mitigate the impact of the fuel disaster, news agencies quoted Kremlin spokesman Dmitry Peskov as saying after Putin met with the emergency and environment ministers.

Ukrainian officials accused Moscow of being reckless. Ukrainian Navy spokesman Dmytro Pletenchuk said: “These are quite old Russian tankers. You can’t go to sea in a storm like that. The Russians violated the operating rules. The result is an accident.”

Commentators pointed out that if the oil products were to enter the Black Sea, they would cause severe ecological damage to the marine environment, already severely affected by the war.

The Volgoneft-212 was 55 years old, registered in St. Petersburg and recently refitted. The middle was cut out and the stern and bow were welded together, creating a huge seam in the middle. This section appears to be broken.

Crew members watched as the helpless ship was destroyed. Video footage showed men wearing orange life jackets standing on the bridge. In addition to a parabolically upward bow, black silt could be seen on the surface. Waves crashed over the damaged hull.

The accident involving derelict Russian boats is the latest maritime disaster off the coast of southern Ukraine. The Black Sea has been a zone of intense military conflict since Vladimir Putin’s large-scale invasion of the country began in 2022.

Ukraine has used naval drones and other missiles to sink part of Russia’s Black Sea Fleet. It was forced to abandon the Crimean port of Sevastopol and relocate to the safer Russian port of Novorossiysk.

In June 2023, Russian troops blew up the Kakhovka dam over the Dnipro River in occupied territory to prevent a Ukrainian military attack. The explosion released 18 billion tons of water, which was in a huge reservoir upstream.

The flood swept away dozens of villages. Water contaminated with fuel, sewage and fertilizers cascaded into the Black Sea. Biologists say the pollution has wiped out mussels and other molluscs, as well as fish and crustaceans.

Scientists have noted an increase in dolphin and porpoise deaths since the Kremlin’s major attack. About 1,000 whales were killed in 2022. Populations of bottlenose dolphins and white-sided dolphins suffered.