Russia and Ukraine have traded accusations over damage to the major Kakhovka dam on the Dnipro River.

"We can already unequivocally declare (this was) deliberate sabotage by the Ukrainian side," Kremlin spokesman Dmitry Peskov said.

"One of the aims was to deprive Crimea of water," Peskov said, adding that the Kremlin "decisively rejected" accusations by Ukraine and the West that Moscow's forces were behind a blast that caused the damage.

"All responsibility lies with the Kyiv regime," Peskov said.

President Vladimir Putin was being briefed on the situation by the defence ministry, Peskov said.

The Kremlin spokesman said Ukraine aimed to "deprive" Crimea, annexed by Moscow in 2014, of water.

He alleged that water entering a key canal in Crimea was "decreasing, sharply decreasing."

The damage to the dam risks flooding thousands and has raised fears for the safety of the Zaporizhzhia nuclear power plant, some 150 kilometres (93 miles) away.