A SHOW OF FORCE…. The expected crackdown on the streets of Tehran, thus far, seems fairly brutal, though I haven’t yet seen reports of fatalities.

One day after Iran’s supreme leader, Ayatollah Ali Khamenei warned of bloodshed if street protests continued over the nation’s disputed elections, witnesses, quoted by news services, said that thousands of demonstrators had attempted to gather for a scheduled opposition protest on Saturday, but that riot police, using tear gas and water cannons, had dispersed them.

Witnesses reported that the black-clad security forces lined the streets of two squares in central Tehran as the city braced itself for a violent crackdown. State television, meanwhile, reported that two people had been wounded at a bomb blast at the Tehran shrine of Ayatollah Ruhollah Khomeini. The report could not be independently confirmed.

There had been varying reports in the hours leading up to the rally about whether it would be called off in the face of the state’s threatened crackdown. State television reported that the leading opposition candidate, Mir Hussein Moussavi, had called off the protest, but some of his supporters, posting on social networking sites, urged demonstrators to gather.

State television had reported that a reformist group called the Combatant Clerics Assembly had called off the rally, saying that “permission was asked to hold a rally, but since it has not been issued, there will be no rally held.”

The AP report added that there were “fierce clashes near Revolution Square in central Tehran after some 3,000 protesters, many wearing black, chanted ‘Death to the dictator!’ and ‘Death to dictatorship!’” It added that “between 50 and 60 protesters were seriously beaten by police and pro-government militia and taken to Imam Khomeini hospital in central Tehran.”

Steve Benen

Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.