Iran's opposition leader said Saturday that a dictatorial "cult" was ruling Iran in the name of Islam — his strongest attack to date on the country's clerical leadership.

Mir Hossein Mousavi also challenged the government to let his supporters take to the streets freely, saying that would allow it to gauge the opposition's true strength. On Thursday, Iran's supreme leader, the Ayatollah Ali Khamenei, charged that the country's opposition had lost its credibility and its right to participate in politics by not accepting the results of June presidential elections.

Khamenei's comments suggest that Iran's opposition will be barred from running in any future elections.

"This is the rule of a cult that has hijacked the concept of Iranianism and nationalism," Mousavi said in an interview published on his Web site, kaleme.com. "Our people clearly understand the difference between divine piety and thirst for power in a religious style ... our people can't tolerate that (dictatorial) behaviors are promoted in the name of religion."

He said the opposition aims to effect reform by raising the consciousness of the Iranian people. "Spreading awareness is the movement's main strategy," he said.

Iran's opposition alleges President Mahmoud Ahmadinejad won the June vote through fraud and that Mousavi was the rightful winner. A massive wave of protests provoked a bloody government crackdown, during which more than 80 demonstrators were killed and hundreds of rights activists, journalists and pro-reform politicians were arrested.

The government, which puts the number of confirmed deaths at 30, has accused opposition leaders of being "stooges of the West" and of seeking to topple the ruling system through street protests.

Meanwhile, the country's hardline leaders have put more than 100 people on a mass trial that began in August. Eleven people have been sentenced to death, and more than 80 others have received prison terms ranging from six months to 15 years.

Iran's rulers point to several recent pro-goverment rallies as an indication that the opposition has lost popular backing.

But Mousavi rejected that claim, and accused the state of busing people in to Tehran to inflate the crowds at Feb. 11 celebrations marking the anniversary of Iran's 1979 Islamic revolution.

"It was an engineered rally ... the biggest number of buses and trains were employed for this rally," he said. He added that there is "no pride" in holding such a rally, and charged that resorting to such tricks is similar to "a dictatorial mentality and methods employed before the revolution."

However, Mousavi acknowledged that the government's bloody crackdown has made it impossible for the opposition to publicly engage in political activities.

He urged the clerical leaders to let opposition supporters take to the streets without being attacked by security forces, saying "how people respond will put an end to all speculation" about the opposition's strength.

Mousavi also warned that shutting down newspapers and blocking Web sites won't help the ruling system silence opposition voices, and asked that his newspaper be allowed to reopen.

Iran's hardline government has closed down dozens of pro-reform papers, including Mousavi's Kalame Sabz, or Green Word, and blocked hundreds of reformist Web sites as part of its efforts to clamp down on opposition activities.

Despite the government's efforts to control the opposition, Mousavi said repression won't stop people from demanding change.

"Tens of millions of Iranians who face censorship, obstruction of their freedoms and repressive measures ... and the spread of corruption and lies, want changes," Mousavi said. "Repressive measures will distance us from a logical solution."