Washington: More than 20,000 Russian soldiers have been killed in Ukraine since December

US intelligence estimates that more than 20,000 Russian soldiers have been killed in Ukraine since December alone, said US National Security Council spokesman John Kirby on Monday.

Around half of them belonged to the Russian mercenary force Wagner, said Kirby in Washington.

Most of them, he said, were "Russian convicts that were thrown into combat (...) without sufficient combat or combat training, combat leadership, or any sense of organizational command and control."

After initial confusion over whether the figures referred to losses in Ukraine as a whole, or only in the battle for the city of Bakhmut, a National Security Council representative confirmed on Tuesday that the estimates were about losses in Ukraine as a whole.

No figures were given for casualties on the Ukrainian side.

The figures cannot be independently verified.

Kirby added there was "very little strategic value" for Russia in retaking the contested city of Bakhmut. "For Russia, this attempted effort, particularly in Bakhmut, has come at a terribly, terribly high cost," Kirby said, referring to the large numbers of casualties.

Russia's military stockpiles and armed forces were depleted, he said, while Ukrainian defences in the areas around Bakhmut remain strong.