TEHRAN, Iran (CNN) -- Iran's ruling system is "going to the slaughterhouse" because of the national outrage over last week's fraudulent presidential election, the Facebook page of Iran's top opposition presidential candidate quoted him Saturday as saying.

Mir Hossein Moussavi, center, is surrounded by supporters in Tehran, Iran, on Thursday.

The post, attributed to Mir Hossein Moussavi, reasserted his call for a new election to be overseen by an independent council.

The authenticity of the message could not be established. It was posted in Farsi and translated by CNN.

The post was responding to Iran's supreme leader Ayatollah Ali Khamenei, who said in a sermon on Friday that President Mahmoud Ahmadinejad got more than 24 million votes -- nearly double the number Moussavi received.

"Eleven million votes difference? Sometimes there's a margin of 100,000, 200,000, or 1 million maximum. Then one can doubt maybe there has been some rigging or manipulation or irregularities. But there's a difference of 11 million votes. How can vote rigging happen?" he asked.

Khamenei's statement confirms a massive manipulation of the vote, according to the Facebook post attributed to Moussavi.

"If the huge volume of vote-rigging -- which has set aflame people's trust in Iran's ruling system -- is going to be used as proof for the lack of rigging, then the system is going to the slaughterhouse," the post stated. "It will also prove the incompatibility of Islam and democracy."

By reaffirming Ahmadinejad's victory, Khamenei and other Iranian authorities "are taking responsibility for what happened," the Moussavi post said.

The statement said a new election "is an absolute right and should be conducted by an independent council" because the Guardian Council -- Iran's election authority -- "has shown it's not an unbiased body."

Early Sunday (late Saturday ET), a statement attributed to Moussavi and posted on his Facebook page said, "Today you are the media, it is your duty to report and keep the hope alive."

In an earlier post on Facebook, Moussavi was quoted as saying he is preparing himself for "martyrdom" and called on his supporters to "protest" and "not go to work."

Journalist Badi Badiozamani contributed to this report.

All About Ayatollah Ali Khamenei • Mahmoud Ahmadinejad • Mir Hossein Moussavi