Iran's new Supreme Leader Mojtaba Khamenei issued a condolence message on March 18 mourning the death of Ali Larijani, his son and several colleagues, in what appears to be his first publicly attributed statement since taking office, IRGC-linked Tasnim reported.

The message is significant beyond its content. Khamenei has not appeared in public since his appointment on March 9, fuelling persistent speculation about the severity of injuries sustained in the US-Israeli strikes that killed his father on February 28.

Khamenei described Larijani as "a learned, far-sighted, intelligent and committed individual with diverse experience across political, military, security, cultural and managerial fields" who had served the Islamic Republic for nearly five decades.

"There is no doubt that the assassination of such a figure shows his importance and the hatred of the enemies of Islam towards him," Khamenei wrote.

He warned that the killings would only strengthen the Islamic Republic. "Those who oppose Islam should know that spilling this blood at the foot of the mighty tree of the Islamic system will only make it stronger. Every drop of blood carries a price that the criminal killers of the martyrs must pay soon."

The statement was addressed to Larijani's wife, children and family, including Ayatollah Amoli Larijani, Ali Larijani's brother and head of the Expediency Discernment Council.

The written message, rather than a video or public appearance, will do little to quell questions about Khamenei's condition. Iranian state media has referred to him as "janbaz," a term used for disabled war veterans.

Iran's ambassador to Russia denied reports this week that the new supreme leader was receiving medical treatment in Moscow.