Russian military bloggers and state-linked commentators have intensified a campaign questioning US President Donald Trump's mental fitness, seizing on remarks he made about Iran to portray him as increasingly erratic.

The claims circulating in Russian-language media centre on Trump's reported statement that Iran had offered to make him its supreme leader, which he said he declined. Military blogger Yuri Podolyaka cited the remark in a post as evidence of what he called a "progressively worsening illness," though he did not specify what condition he was referring to.

A screenshot of Podolyaka's Telegram post, from his channel "Мир сегодня с Юрий Подоляка" (The World Today with Yuri Podolyaka), showed the blogger writing: "We're losing him. In my opinion, the disease is clearly progressing. Grandpa Biden already seems more sane to me than this clown. Although... they're both equally unfit."

The posts came as Trump himself issued a stark warning to Iranian negotiators on March 26, saying Tehran was "begging" Washington for a deal after being "militarily obliterated, with zero chance of a comeback."

"They better get serious soon, before it is too late, because once that happens, there is NO TURNING BACK, and it won't be pretty," Trump wrote on Truth Social.

Podolyaka, who has a large following across Russian-speaking countries, did not specify what condition he was referring to. Military correspondent Nikolai Dolgachev has previously claimed, citing an unnamed psychiatrist acquaintance, that Trump showed signs of mania linked to a seasonal episode. Russian state media has also referred to Trump, citing unnamed doctors, as "a classic patient for an acute psychiatric ward."

None of the claims are sourced to verified medical professionals or official diagnoses.