TEHRAN—Iranian media on Saturday published photographs and video of Supreme Leader Ayatollah Ali Khamenei attending a religious ceremony in Tehran, amid speculation about the octogenarian’s health among foreign diplomats, on social media and in published reports. Mr. Khamenei’s health has declined in recent weeks, rekindling talk in Iran’s ruling circles about a succession plan, according to an Iranian official and people close to the government. The 83-year-old leader’s medical condition is treated as close to a state secret in Iran. There has been no official confirmation that he has had recent medical problems, but he is known to have had heart and prostate problems in the past.

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