Sickly Vladimir Putin will die of cancer very soon, Ukraine’s spy chief has said. The ‘prophecy’ comes as a leading cheerleader for Russia’s war claimed the race for his crown is under way as rival camps in the Kremlin jostle to seize power.

Rumours have persisted that Putin is “critically ill” after he became bloated and was seen trembling and shaking alarmingly.

Bombshell spy emails leaked to British media appeared to confirm he has early-stage Parkinson’s disease and pancreatic cancer. Sources also claimed he had emergency surgery last year and was shadowed by a team of top doctors.

Consequently, Russian officials are already planning to replace Vladimir Putin as leader eleven months after he invaded Ukraine, a former loyalist has claimed.

Igor Strelkov, an ex-FSB colonel who was key to Putin’s annexation of Crimea, also claims a mass mobilisation of 500,000 Russian men is the only way Putin will defeat Ukrainian forces.

Speaking on video, the now-staunch Putin critic said: “The fight for the political Olympus has begun between the groupings that surround Putin. The battle to replace him is raging to the extent that ‘even we can notice it”.

The fight at the top focuses on insurgent Putin crony Yevgeny Prigozhin, and loyalist forces in the defence ministry around weakening defence minister Sergei Shoigu, according to Strelkov.

Nikolai Patrushev, ex-FSB head, is another name likely to pull the trigger on Putin in a bid to save the elite ruling circle.

His son, agriculture minister Dmitry Patrushev, is also another figure circulating if Putin loses the war or deteriorates due to ill health.

Talking about Prigozhin, who was once Putin’s chef, Strelkov said: ‘His latest appearances in the media clearly showed that now he positions himself not just like a war commander, but as a public and a political figure…

“Prigozhin stands against the grouping which Shoigu either heads or belongs to. They have already started to fight. It was like a “feudal” battle. The military crisis led to a power crisis. In turn the power crisis will deepen the military crisis. And it’ll keep going down the spiral, unless urgent measures are taken.”

Strelkov said there could be a second or even a third wave of mobilisation to try and win the war in Ukraine.

Telegram channel General SVR claimed Putin has approved plans to call up two million for mobilisation this year. The first to be called will be men in debt to their ex-wives over alimony payments, it was claimed.

Kyrylo Budanov, Ukraine’s chief of defence intelligence, said last night he is certain Putin does have terminal cancer. He told ABC News, “He has been sick for a long time. I am sure he has cancer. I think he will die very quickly. I hope very soon.”

He added his security agency has obtained intelligence from sources close to the Kremlin despot. Budanov said, “We just know it – from people, from sources.”

He believes Putin will die soon but not before a humiliating final defeat in Ukraine. The spy chief said, “This war must end before his death… We will win it in 2023.”

He also said there will be a change of power in Russia after the death of Putin, who has ruled for more than two decades. Budanov explained, “We should not be afraid of its transformation, as it will benefit the whole world.”

However, others warned the future direction of the regime is far from certain. It depends on the outcome of a power struggle that has already begun in anticipation of Putin’s exit, said Russian war analyst and former loyalist Igor Strelkov.

“The fight for the political Olympus has begun between the groupings that surround Putin,” he said. He added battle to replace him is raging to the extent that “even we can notice it”.

Strelkov, a former colonel in the FSB spy agency, was a key figure in Putin’s annexation of Crimea and subjugation of the Donetsk region of Ukraine in 2014. He was among three convicted by a Dutch court in November for downing Malaysia Airlines flight MH17, killing all 298 on board. Despite this, he remains a key voice inside Russia on the conduct of the war.

The staunchly pro-war blogger, real name Igor Girkin, said the immediate mobilisation of another half a million men is the only way for Putin to avoid defeat and ignominy in Ukraine.

But he suggested a “feudal” battle among rivals to replace Putin is stoking a “military crisis” for Russia.

He claimed the fight at the top of the Kremlin focuses on insurgent Putin crony Yevgeny Prigozhin, head of the Wagner private army, and loyalist forces in the defence ministry around weakened defence minister Sergei Shoigu.

Others believe security apparatchiks around ex-FSB head Nikolai Patrushev – secretary of the powerful security council – are more likely to pull the trigger on Putin in a bid to save the elite ruling circle if the war continues to go wrong.

Some claim the security bloc is lining up his son, Agriculture Minister Dmitry Patrushev, as the frontman to replace Putin if he is forced out by war setbacks or ill health.

Strelkov sees Prigozhin, a fixer dubbed Putin’s “chef” as he was in charge of Kremlin banquets, as aiming to be a major political force in his own right.

And he said there is evidence he was now securing prominent coverage in the state media. There has been speculation he wants to become Defence Minister – or even president.

“The grouping of Yevgeny Prigozhin stands against grouping which includes Sergei Shoigu,” said Strelkov.

“They have already started the fight. They are not fighting over the number of shells… Now we are speaking about what comes after Putin. Will it happen in one year or two? We don’t know. But factually the fight for the political Olympus has begun between the groupings that surround Putin to the extent that even we can notice it.”

• A Tell / Agencies report