Iran's supreme leader Ayatollah Ali Khamenei has made a public appearance amid rumors about his health.

State television aired images Sunday of the 75-year-old Khamenei addressing a group of environmental officials and activists at his residence in central Tehran. He appeared to be comfortable and healthy in the footage.

Foreign-based news websites in recent days have claimed that Khamenei, who has the final word on all matters in Iran, had been hospitalized in critical condition.

Khamenei has been Iran's top leader since 1989. In September, he underwent prostate surgery and spent about a week in the hospital before being released.

Iran is in the middle of critical negotiations with world powers over its contested nuclear program. Khamenei has backed Iran's negotiators publicly in the talks.