Ukraine's security services have reportedly claimed an intercepted phone call shows Russian involvement in the collapse of Kakhovka dam earlier this week.
Thousands of people have been evacuated from the affected regions in the country's south, and there have been warnings of a humanitarian crisis.
Both Kyiv and Moscow have blamed one another for the collapse, but Reuters reported further evidence of an attack was emerging.
Reuters reported the Security Service of Ukraine (SBU) claimed to have intercepted a telephone call that implicated a Russian "sabotage group".
According to one of the people on the call, identified by the SBU as a "Russian soldier", the alleged attack "didn't go according to plan".
"(The Ukrainians) didn't strike it. That was our sabotage group," the man is reported as saying.
Meanwhile, Norwegian researchers gathered seismic information that showed signs of an explosion, and US spy satellites detected the same, an official told the New York Times.
The Kakhovka hydroelectric dam and reservoir, essential for drinking water and irrigation for a huge area of southern Ukraine, lies in a part of the Kherson region occupied by Moscow's forces for the past year.
It is also critical for water supplies to the Crimean Peninsula, which was illegally annexed by Russia in 2014.
Historic Ukrainian cathedral badly damaged in Russian strikes
Ukraine holds the western bank of the Dnieper, while Russia controls the eastern side, which is lower and more vulnerable to flooding.
Scenes of flooded communities and rescues by boat and from rooftops called to mind a natural disaster, rather than those usually seen in war.
The flooding could wash away this season's crops, while the depleted Kakhovka reservoir would deny adequate irrigation in the years ahead.
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