The southern command of Ukraine's Armed Forces said on Tuesday that the Kakhovka dam in the Russian-controlled parts of Ukraine's Kherson region was blown up by Russian forces.
"The scale of the destruction, the speed and volumes of water, and the likely areas of inundation are being clarified," the command said on its Facebook page.
Russia's TASS agency reported that the dam collapsed and the nearby territories were flooding.
Reuters was unable to immediately verify the Ukrainian statement.
What is the Kakhovka dam, and what impact does blowing it up have?
SIGNIFICANCE OF THE DAM
* The dam, 30 metres (98 feet) tall and 3.2 km (2 miles) long, was built in 1956 on the Dnipro river as part of the Kakhovka hydroelectric power plant.
* The reservoir also supplies water to the Crimean peninsula, annexed by Russia in 2014, and to the Zaporizhzhia nuclear plant, which is also under Russian control.
* The volume of water in the reservoir is about equal to the Great Salt Lake in the U.S. state of Utah.
* Blowing the Soviet-era dam, which is controlled by Russia, would unleash a wall of floodwater across much of the Kherson region.
(Reporting by Guy Faulconbridge; Editing by Michael Perry)
