MOSCOW Russia's defence minister said on Tuesday his forces had thwarted the first three days of a Ukrainian counter-offensive in battles that had left more than 3,700 Ukrainian soldiers dead or wounded.

Defence Minister Sergei Shoigu made the claim in an unusually detailed statement reporting on alleged losses by both sides. Ukraine has maintained deliberate ambiguity about whether its long-expected counter-offensive is under way, and Reuters could not independently verify the battlefield claims.

"In the past three days, the Ukrainian regime launched a long-promised offensive in different sectors of the front," Shoigu said.

"The attempts at an offensive were thwarted, the enemy was stopped," he added. "The enemy did not achieve its goals but suffered significant and incomparable losses."

He said Ukraine lost 3,715 men over three days, as well as 52 tanks and 207 armoured vehicles. Russia lost 71 soldiers and 210 were wounded over the same period in the battles. Russia lost 15 Russian tanks and nine armoured vehicles, he said.

Russia said on Monday that Ukraine had begun its long-awaited counter-offensive by trying to pierce the Russian front in the south of the Donetsk region.

On Monday, Ukraine attacked at seven points along the front but with significant losses of over 1,600 men, Shoigu said.

Ukraine dismissed the Russian statements as lies but gave no details on the attacks - or their outcome.

Shoigu accused Ukraine for destroying the Kakhovka dam in the south of the country in the early hours of Tuesday, saying it was a tactic to provide cover for Kyiv to redeploy units in the region for offensive operations.

"The Kyiv regime committed another terrorist crime: the Kakhovskaya hydroelectric power plant was blown up, which led to the flooding of significant territories," Shoigu said.

Ukraine and its Western allies say it was Russia that blew up the dam.

(Reporting by Guy Faulconbridge; Editing by Mark Trevelyan)