Vladimir Putin is terminally ill with cancer and will die very soon, Ukraine's military intelligence head has claimed.

Kyrylo Budanov, without providing evidence, said he knows the Russian despot's death is imminent due to an ongoing illness from cancer.

Budanov, who is the Main Intelligence Directorate of the Ministry of Defense of Ukraine, discussed the ongoing war and the Russian leader in an interview with ABC News on Wednesday. 

He added that he expects there to be a transfer of power to another Russian crony following Putin's demise.

ABC News' Britt Clennett asked Budanov if Putin was terminally ill, with the spy chief immediately responding 'of course'.

Budanov, in his non-native English, added: 'He is ill long period.'

Asked when he thinks Putin's death will come, Budanov said that he thought it would be very soon.

'I think very fast. I hope.'

Speculation about Putin's health has been ongoing for several years. The 70-year-old Russian leader has been rumoured to be suffering from cancer, Parkinson's Disease and numerous other ailments.

'We think it's cancer,' Budanov said.

'We know it from human sources' that are close to Putin, he added.

Budanov was also asked what he thought would happen following Putin's death, whether someone from within the Kremlin would take over and if the war in Ukraine would continue.

He responded saying he expected that there would be 'a replacement and transfer of power', suggesting that this would be to one of Putin's cronies.

'This war should be ended before [Putin] is dying,' Budanov added.

Telegram channel General SVR, which purports to have a number of insider sources in the Kremlin, said Putin's doctors recently noted a 'significant deterioration in his health' and recommended that he step away from any public appearances so he can rest. 

The Telegram channel also reported that Putin now gets tired very quickly.

He is also prone to 'frequent bouts of dizziness and headaches', as well as 'clouding of consciousness', it added.

The reports of Putin's poor health have been supported by the cancellation of a number of planned trips and public engagements.

Just last week, on December 28, Putin pulled out of a planned trip to Pskov, a city near the Estonian border. The cancellation was officially blamed on 'unfavourable flying conditions' but weather forecasts suggested the skies were clear.

A visit to Russia's biggest tank plant in Nizhny Tagil, in the Ural mountains was also shelved. Even the usual appearance at an end of year meeting of his government ministers was cancelled.

Putin also refused to proceed with his traditional December press conference, which typically sees the president speak for up to four hours and field questions from journalists and viewers. Even Putin's beloved end-of-year ice-hockey game was cancelled.

The head of Ukraine's military intelligence Kyrylo Budanov has claimed Vladimir Putin is terminally ill with cancer and will die very soon.

If Putin does die, there are a number of prominent actors who could take over.

Since Putin's war began, Putin's allies like Chechen warlord Ramzan Kadyrov and Wagner boss Yevgeny Prigozhin have begun jockeying for power and prominence, suggesting that they could one day want to supplant him. 

Ukrainian intelligence believes Putin's domestic policy tsar Sergey Kiriyenko, former FSB chief Nikolai Patrushev, and his son Dmitry Patrushev could also be positioning themselves for a takeover.