Russia declared a regional state of emergency on Saturday in Crimea, which it seized from Ukraine in 2014, as workers cleared tons of contaminated sand and earth on either side of the Kerch Strait following an oil spill in the Black Sea last month.

Russian President Vladimir Putin calls the incident an "ecological disaster" as officials and volunteers attempt to clean beaches contaminated with the heavy oil.

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.