Ukrainian President Volodymyr Zelensky has said about 16,000 Russian troops have now been killed as the war entered its fifth week.

Zelensky's troops are preparing to take back the city of Kherson today, which was the first major city the invading forces took control of.

An adviser to the Ukrainian defence minister said he feels the city would be won back today.

Markian Lubkivskyi told BBC Radio 4's Today programme: 'I believe that today the city will be fully under the control of Ukrainian armed forces.

'We have finished in the last two days the operation in the Kyiv region so other armed forces are now focused on the southern part trying to get free Kherson and some other Ukrainian cities.'

Zelensky also welcomed delivery of 1,500 German anti-aircraft missiles, while Putin was said to be scaling back his invasion aims to 'liberating' Ukraine's eastern Donbas region as he continued to shell civilians.

Zelensky said: 'Over the past week, our heroic Armed Forces have dealt powerful blows to the enemy. Significant losses.'

'I am grateful to our defenders who showed the occupiers that the sea will not be calm for them even when there is no storm. Because there will be fire.

By restraining Russia's actions, our defenders are leading the Russian leadership to a simple and logical idea: talk is necessary. Meaningful. Urgent. Fair. For the sake of the result, not for the sake of the delay.'

Zelensky said the devastation of Mariupol was getting worse, with tens of thousands trapped in the southeastern city without water, food or heating.

He said: 'The situation in the city remains tragic. Absolutely tragic. The Russian military does not allow any humanitarian aid into the city.'

The Kremlin has disputed that 16,000 Russian troops have been killed, claiming the figure is just 1,351. Ukraine's General Staff of the Armed Forces said its troops were continuing to fend off Russian attacks on Kyiv.

It said Russia has had trouble replacing its fighters after a series of hard-fought battles and that the Kremlin's equipment was in 'poor technical condition' because of 'negligent prior exploitation and prolonged storage'.