Rumors surface on social media that Ayatollah Ali Khamenei has died after undergoing surgery for cancer.

Posts on social media indicate that Iran's Supreme Leader, Ayatollah Ali Khamenei, has died, Breitbart News reports Sunday, although no official announcement has yet been made.

Two well-known journalists from Cairo and Israel tweeted that Khamenei had died Saturday after a bout with prostate cancer, noting that the information stems from "reliable sources."

Khamenei was urgently brought to a hospital in Tehran after several of his bodily systems had already failed, Arab media reported Thursday; Iranian media outlets confirmed the news Friday.

Rumors that he was suffering from prostate cancer that had metastasized to multiple systems have persisted for months. The 76 year-old dictator underwent surgery earlier this week; the latest reports had indicated that he was in critical condition.

Despite the lack of official confirmation over his death, speculation has already begun over his successor, whom Khamenei has not yet formally named.

Khamenei has called for Israel’s destruction several times in the past. Recently, the Iranian leader accused Israel of having "no limit or boundaries regarding viciousness, cruelty, and trampling underfoot all human standards and ethnics. Crimes, genocide, mass destruction, the killing of children, women and the homeless...they take pride in."

He previously said on Twitter that the Israel government was “the most wicked terrorist” in the world.

Khamenei has also called Israel an "illegitimate and bastard regime," and further called the United States a "smiling enemy" that is not to be trusted.