Volunteers are grappling with environmental havoc across more than 35 miles of coastline, after at least 3,700 tons of heavy oil spilled into the Kerch Strait.

Volunteers helping to clean up a major oil spill along Russia's Black Sea coast appealed in a video released on Monday for President Vladimir Putin to urgently send federal aid, saying that they and local authorities were overwhelmed.

Russia’s top investigator Alexander Bastrykin has ordered law enforcement authorities to launch a criminal investigation into alleged “failures” in addressing the cleanup of a major oil spill along the Black Sea coast in southern Russia.

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Slovakia’s prime minister held surprise talks with Vladimir Putin on Sunday amid a stand-off with Ukraine over gas supplies.