Hossein Mousavi challenged the government

Hijacked the concept of Iranianism and nationalism," Mousavi said 

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. Two days ago, Iran's supreme leader, Ayatollah Ali Khamenei, charged that Iran's the opposition had lost its credibility and its right to participate in politics by not accepting the results of June presidential 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 website. "Our people can't tolerate that [dictatorial] behaviours are promoted in the name of religion." The opposition alleges President Mahmoud Ahmadinejad won the vote through massive fraud and that Mousavi was the rightful winner. A massive wave of protests provoked a bloody government crackdown, in which more than 80 demonstrators were killed and hundreds of rights activists, journalists and pro-reform politicians were rounded up.

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

Meanwhile, it has 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 been handed prison terms ranging from six months to 15 years.

Mousavi himself is free, in Tehran.

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

But Mousavi accused the state of abusing in people to inflate the crowds at a February 11 rally marking the anniversary of Iran's 1979 Islamic revolution. And he asked the government to let opposition supporters to take to the streets without being attacked or killed by security forces.

"Allow the Green Movement to invite people to a rally," Mousavi said. "How people respond will put an end to all speculation" about its strength, he added