Mondtazeri (at left) never names Supreme Leader Ayatollah Khamenei directly in his remarks, but he has long been an outspoken opponent of both Khamenei and the government of President Mahmoud Ahmadinejad.
Montazeri says "those who have lost, religiously and reasonably, the credibility for serving the public, are automatically dismissed, and the continuation of their work has no legitimacy."
The Grand Ayatollah also says Iranians have a religious right and duty to protest their leaders, if those leaders violate the tenets of Islam by usurping power.
"People must express their opinion about the illegitimacy and lack of their approval of their performance, and seek their dismissal through the best and least harmful way. It is clear that this is a societal duty of everyone, and all the people, regardless of their social positions and according to their knowledge and capability, must participate in this endeavor, and cannot shirk their responsibility."
Montazeri's comments, which came in the form of answers to questions posed by one of his former pupils, were reported by the new, independent, Web-based news outlet Tehran Bureau. He issued the statements as Islamic "fatwas," or religious decrees.
Dr. Majid Tafreshi, a historian and expert on Iran's post-revolutionary cleric-led government, tells CBSNews.com that Montazeri's comments were "not unexpected, but they were his harshest comments" yet on the election results, which opposition leaders claim were manipulated to give Ahmadinejad a landslide victory.
Khamenei was quick to endorse Ahmadinejad as the winner of the vote and is widely seen as a firm backer of the hard-line president.
Tafreshi says that while Montazeri, "did not mention Khameni by name, these were very direct statements."
Despite Montazeri's senior role in the clerical establishment in both Iran and the wider Muslim world — he is one of only two figures to carry the title "Source of Emulation" for Shiite Muslims — Tafreshi warns that his increased rhetoric against the Iran's rulers won't "change everything over night".
What the Grand Ayatollah's remarks do, however, is demonstrate the very clear ideological split among the clerics which, for the first time, the Supreme Leader and the government do not seem to be able to heal.
Tafreshi says Montazeri's statements will likely "increase tension" in Iran – fueling the battered opposition movement and possibly keeping the dwindling protests going.