A Russian oil tanker carrying thousands of tonnes of oil products split apart during a heavy storm on Sunday, spilling oil into the Kerch Strait, while another tanker was also in distress after sustaining damage, Russian officials said.
At least one person was killed.
The 136-metre Volgoneft 212 tanker, with 15 people on board, was split in half with its bow sinking, footage published by state media showed, with waves washing over its deck.
The Russian-flagged vessel, built in 1969, was damaged and had run aground, officials said.
"There was a spill of petroleum products," said Russia's water transport agency, Rosmorrechflot.
A second Russian-flagged ship, the 132-metre Volgoneft 239, was drifting after sustaining damage, the emergency ministry said. It has a crew of 14 people and was built in 1973.
Both tankers have a loading capacity of about 4,200 tonnes oil products.
Official statements did not provide details on the extent of the spill or why one of the tankers sustained such serious damage.
The vessels were in the Kerch Strait between mainland Russia and Crimea, which Russia annexed from Ukraine in 2014, when they issued distress signals.
Russia said more than 50 people and equipment, including Mi-8 helicopters and rescue tugboats, had been deployed to the area.
Russia's Kommersant newspaper reported that the Volgoneft 212 tanker was carrying about 4,300 tonnes of fuel oil.
Unverified video posted on Telegram showed some blackened water on stormy seas and a half-submerged tanker.