KYIV -- Ukraine's domestic security service said on Friday it had intercepted a telephone call proving a Russian "sabotage group" blew up the Kakhovka hydroelectric station and dam in southern Ukraine.

The destruction of the facility on Tuesday unleashed mass flooding, forcing thousands of residents to flee and wreaking environmental havoc.

The Security Service of Ukraine (SBU) posted a one-and-a-half-minute audio clip on its Telegram channel of the alleged conversation, which featured two men who appeared to be discussing the fallout from the disaster in Russia.

Reuters could not independently verify the recording. Russia, which has accused Kyiv of destroying the dam, did not immediately comment on its content.

"They (the Ukrainians) didn't strike it. That was our sabotage group," said one of the men on the recording, described by the SBU as a Russian soldier. "They wanted to, like, scare (people) with that dam."

"It didn't go according to plan, and (they did) more than what they planned for."

The man also said "thousands" of animals had been killed at a "safari park" downstream as a result.

The other man on the line expressed surprise at the soldier's assertion that Russian forces, which were occupying the dam following Russia's full-scale invasion in February 2022, had destroyed the hydroelectric plant and dam.

The SBU offered no further details of the conversation or its participants. It said it had opened a criminal investigation into war crimes and "ecocide."

"The interception by the SBU confirms that the Kakhovskaya HPP (Hydroelectric Power Plant) was blown up by a sabotage group of the occupiers," the SBU said in a statement. "The invaders wanted to blackmail Ukraine by blowing up the dam and staged a man-made disaster in the south of our country."

Hundreds of Ukrainians were rescued from rooftops in the flooded areas on Thursday. The governor of the southern region of Kherson said some 600 square kilometres, or 230 square miles, of the region were underwater.

"By blowing up the Kakhovskaya HPP dam, the Russian Federation definitively proved that it is a threat to the entire civilized world," SBU chief Vasyl Malyuk was quoted as saying in the statement.

"Our task is to bring to justice not only the leaders of Russian President Vladimir) Putin's regime, but also the ordinary perpetrators of crimes," he said.

(Reporting by Dan Peleschuk, Editing by Timothy Heritage and Andrew Heavens)