The losses are proving costly for Russian commanders, who are being forced to rely on poorly trained recruits to advance at pace in eastern Ukraine and mount a counter-offensive against Kyiv’s occupation of the Russian region of Kursk.

“They do have mass, they can push more people onto the front line than the Ukrainians,” a Western official said.

“But it’s worth noting the difference in the training, the quality and the standard of those forces Russia puts on the front line, some of them only days of training and regularly with only weeks of training, so they’re not able to capitalise on some of these advances that they’ve made.”

The size of Russia’s army

The source said Russia was likely able to recruit at a rate of 1,000 troops a day as it looks to plug losses in its manpower.

The size of Russia’s population – about 146 million – is one of Putin’s most potent weapons in a war of attrition against Ukraine.

Since the beginning of the war, Putin has ordered two official increases in the number of combat troops – by 137,000 and 170,000 respectively.

The Russian president also mobilised some 300,000 soldiers between September and October 2022, in a move that saw tens of thousands of military-aged men flee the country.

The Kremlin insists it has no new plans to mobilise more forces to fight in Ukraine, as it relies on volunteers.

Experts said the Russian economy, which has been ravaged by Western sanctions and the cost of fighting, might not be able to stomach the bill for the military increases.

Dara Massicot, a Russian military expert at the Carnegie Endowment for International Peace, said: “There are ways to staff a standing 1.5 million force but the Kremlin will not like them if they are truly grappling with what that requires.

“Are they really able to boost the defence budget to sustain procurement and this requirement?”

It had recently been reported that the Kremlin was paying volunteers from the Moscow region up to £50,000 in wages and bonuses to fight in Ukraine – about four times the average annual wage.

The government paid out about three trillion rubles (£27 billion) in salaries and compensation to soldiers and their families between July 2023 and June 2024, according to researchers Re:Russia.

The figure amounts to about 1.6 per cent of Russia’s expected gross domestic product for the year, as well as about 8 per cent of its federal budget expenditure.