Deaths of Russian generals reveal army's failures - but there is another reason this is a big deal

The mounting death toll of Russian generals in the Ukraine conflict reveals major deficiencies in Vladimir Putin's war machine, according to one expert.

The Ukrainian army on the weekend claimed its forces killed a seventh Russian general since the start of the war on February 24.

Matthew Sussex, a senior fellow at the Centre for Defence Studies at the Australian Defence College in Canberra, said the Russian army could ill afford to lose its senior commanders in combat.

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"The deaths of generals as well as other officers such as majors and colonels means the Russian army is losing about 20 years' experience with every one," Associate Professor Sussex told nine.com.au.

He said junior commanders were ill equipped to take over command because the Russian army has a system of concentrating major decisions with its senior commanders.

The Ukrainian military has claimed it has killed seven Russian generals during fighting.

Associate Professor Sussex said the targeting of Russian generals by Ukraine aimed to "decapitate" the chain of command by using snipers, drones and anti-tank weapons.

The most recent was Lieutentant-General Yakov Rezantsev during fighting in the Kherson region in Ukraine's south.

The Ukrainian army said he was commander of the 49th Combined Arms Army of the Southern Military District of the Russian Federation.

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Russia's defence ministry has not commented on the Ukrainian claim.

Associate Professor Sussex said a major communications breakdown in the Russian army was also helping the Ukrainian military pinpoint enemy movements.

"There encrypted phones haven't been working ... they've had to resort to using mobile phones over the Ukraine network."

He also said the Russian army's command and control structure in Ukraine was hampered by not having a single commander in chief. Instead the four invasion sectors each had its own senior officer in charge.

- Reported with CNN