Russian President Vladimir Putin's days might just be numbered – and when his time is finally up, it's "not going to be pretty".

That's according to former CIA Moscow chief of station Daniel Hoffman, who told the Daily Beast in an explosive new interview that he was convinced the 69-year-old would be assassinated.

He told the publication his advisers would turn on him the minute they grew unhappy with either their personal positions, or the progress of the war in Ukraine.

"Nobody's gonna ask, 'Hey Vladimir, would you like to leave?' No. It's a f***ing hammer to the head and he's dead. Or it's time to go to the sanatorium," Hoffman said.

"They schwack him for it. That's what they'll do."

He told the publication's national security reporter Shannon Vavra that Putin's rivals would give little warning before making their potentially bloody move.

"These guys that are going to do it are going to be so secret about it so that Putin doesn't find them and kill them first," Hoffman said.

"It'll happen all of a sudden. And he'll be dead."

And when it came to who those rivals could be, Hoffman was not afraid to name names, listing Nikolai Patrushev, the head of the Russian federal police's Security Council, Alexander Bortnikov, the director of the FSB, and Defence Minister Sergei Shoigu as likely culprits.

Nikolai Patrushev's name has consistently popped up as a potential Putin successor with the 70-year-old building up a reputation for brutality, with the Telegram channel "General SVR" recently reporting that he would be the "worst option" to replace Putin.

"Patrushev is an outright villain. He is no better than Vladimir Putin," the narrator claimed.

"Moreover, he is a more cunning, and I would say, more insidious person than Vladimir Putin. "If he comes to power, Russians' problems will only multiply."

Another potential contender is Alexander Bortnikov, a member of Putin's inner circle.

In March, he was named by the Defence Intelligence of Ukraine (DIU) as a potential option, having held his current position since 2008.

And Sergei Shoigu – Russia's popular, longest-serving cabinet member – is also widely considered to be a possible replacement option, with Al Jazeera last year writing that "Shoigu is often seen on TV fishing and hunting with Putin – a symbolic anointment that some say makes him the most likely successor".

"He has serious chances, much higher than anyone else for now," Nikolay Mitrokhin, a researcher with Germany's Bremen University, told Al Jazeera at the time.

All three men are key members of the Russian "siloviki" – the term given to former military personnel who are now in political positions – with the group emerging as a growing threat to Putin's rule.

The speculation comes amid never-ending rumours regarding Putin's health, following a series of reports he was suffering from serious conditions such as cancer or Parkinson's, based on changes to his appearance and his newly fidgety behaviour in public.

Ukrainian spy chief Major General Kyrylo Budanov told USA Today that he believes Putin will die in the next two years as he suffers from "grave illnesses".

"Putin doesn't have a long life ahead of him," he said.

Russian President Vladimir Putin greets officers during the wreath laying ceremony at the Tomb of the Unknown Soldier near the Kremlin. Photo / Getty

Russia's massive blow

Meanwhile, Russia's economic woes continue to seriously worsen, with the nation defaulting on its foreign-currency sovereign debt for the first time since 1918 after the grace periods on two eurobond coupons worth around $US100 million ($A144 million) expired over the weekend.

The default was the result of a string of sanctions imposed on Russia by Western nations as a direct result of the deadly invasion of Ukraine, which has been raging since February 24.

Predictably, Russia's Finance Minister Anton Siluanov slammed the situation as a "farce", insisting Russia was able to pay the debt.

"Anyone can declare whatever they like," Siluanov said.

"But anyone who understands what's going on knows that this is in no way a default."

And the rogue nation will also cop another major blow this week which will see it left out of pocket by "tens of billions of dollars" thanks to a tough new ban on Russian gold by G7 nations.

The leaders of Canada, France, Germany, Italy, Japan, the United Kingdom and the United States are currently meeting in Munich, Germany for the latest summit, where they resolved to rollout out the crackdown this week.

The news was confirmed by US President Joe Biden on Sunday soon after reports of a gold ban first leaked.

"The United States has imposed unprecedented costs on Putin to deny him the revenue he needs to fund his war against Ukraine," Biden tweeted.

"Together, the G7 will announce that we will ban the import of Russian gold, a major export that rakes in tens of billions of dollars for Russia."

- Alexis Carey, news.com.au