Putin has to break from meetings to take medical treatment continually, said one former spy.
Christopher Steele told British talk radio station LBC of "increasing disarray in the Kremlin."
Steele's comments follow weeks of rumors about the Russian president's health.
President Vladimir Putin's grip on power is fading, and he has to take regular breaks for medical treatment, according to former British spy Christopher Steele.
"Our understanding is that there's increasing disarray in the Kremlin and chaos," Steele said in an interview with British talk radio station LBC on Wednesday.
Steele is a former MI6 operative who worked for many years in Russia, including heading up the spy agency's Russia desk for three years.
He told LBC: "There's no clear political leadership coming from Putin, who is increasingly ill, and in military terms, the structures of command and so on are not functioning as they should."
He did not cite his sources but said he was "fairly confident" of his claims. Putin's top spokesperson, Dmitry Peskov, has repeatedly denied any issues.
"What we do know is that he's constantly accompanied around the place by a team of doctors," said Steele. Government meetings - many of which are televised - have to be broken up into sections so that Putin can go out and receive regular treatments, Steele claimed.
"It's certainly having a very serious impact on the governance of Russia at the moment," he said.
Putin is unlikely to withdraw from Ukraine "because of the sort of political corner he's painted himself into," Steele said. He added: "It's probably driving his wish to solidify his legacy as he sees it."
Rumors about Putin's health have circulated for months. On May 14, Ukraine's head of military intelligence, Maj. Gen. Kyrylo Budanov told Sky News that Putin is "very sick" and suggested that a Kremlin coup is underway.
And the rumors went into overdrive after recent television appearances revealed the president looking pained, fidgety, and puffy. They led to speculation that the president may have dementia, Parkinson's disease, or a type of cancer.
Some tabloid speculations have been attributed to an anonymous Telegram account named "General SVR." It claims to be a former high-ranking Kremlin official but Insider has been unable to verify.
But in his interview with LBC, Steele gave credence to the Parkinson's rumor, saying Putin is "probably" ill with the disease. Nonetheless, "we don't know the exact details of what his ailment is," Steele said.
In April, an in-depth investigation by the independent Russian outlet Proekt also found, by examining flight records, that Putin has for the last decade had a medical entourage, with up to a dozen doctors with him at any one time - including numerous visits from a thyroid cancer specialist.
Steele is the author of the Trump-Russia dossier that included obscene allegations about the former US president, including the rumored "pee tape."
No evidence has since been found of that tape, and other headline claims have been discredited or are yet to be independently confirmed, as CNN reported.