The daytime protests across the Islamic republic have been largely peaceful. But Iranians shudder at the violence unleashed in their cities at night, with the shadowy vigilantes known as Basijis beating, looting and sometimes gunning down protesters they tracked during the day.

The vigilantes plan to take their fight into the daylight on Friday, with the public relations department of Ansar Hezbollah, the most public face of the Basij, announcing that they planned a public demonstration to expose the “seditious conspiracy” being carried out by “agitating hooligans.”

“We invite the vigilant people who are always in the arena to make their loud objections heard in response to the babbling of this tribe,” said the announcement, carried on the Web site Parsine.

The announcement could be the first indication that the government was taking its gloves off, Iranian analysts noted, because up to this point the Basijis, usually deployed as the shock troops to end any public protests, have been working in stealth.