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.

"It is the special brigades of the Revolutionary Guards who right now, especially at night, trap young demonstrators and kill them,” said Mohsen Sazegara, an Iranian exile who helped write the charter for the newly formed Revolutionary Guards in 1979 when he was a young aide to Ayatollah Ruhollah Khomeini.

"That is one way the regime avoids the responsibility for these murders. It can say, ‘We don’t know who they are.’ ”
The death toll now stands at 13, said Shahram Kholdi, a graduate student at the University of Manchester in England, who is building a Web site to track all killings.

Mir Hussein Moussavi, the opposition presidential candidate leading the fight to overturn the results of last week’s presidential campaign, published two letters on his Web site on Thursday decrying the violence being carried out by the Basij.

In one letter, he said an otherwise peaceful day of protest last Monday had been sullied when seven people were killed, although he did not name the Basij directly.

"They tried to turn the sweetness of this most glorious gathering into beastly confrontations to leave a bitter taste in the mouth of the lovers of Iran,” he wrote.

Calling the vigilantes the "disciples of fraud and lies,” he said they destroy both public and private property to spread fear and chaos and to give the police an excuse to crack down on peaceful demonstrators.

In the second letter, to the National Security Council, he went further in depicting the vigilantes’ role as agents provocateurs.
Saying that the Basijis lack uniforms, proper identification or anything that denotes them as public employees, he said they appeared with hoses, clubs, iron bars, truncheons and sometimes firearms.

"Just before the police show up they attack the demonstrations,” he wrote. "They try to provoke the demonstrators and they destroy people’s property and vehicles.” Mr. Moussavi said the security forces did nothing to stop them.

The Iranian government said shots were fired from a Basij base near the rally on Monday because the men inside feared that the building was under attack.

The word Basij means roughly mass mobilization in Persian, and the original organization consisted of all the civilian volunteers whom the Ayatollah Khomeini urged to go fight on the front in the Iran-Iraq war. Some of them died while tromping across mine fields toward Iraq.

The Basij was reinvented in the late 1990s, Iran experts said, after the government felt that it had lost control of the streets during spontaneous celebrations when Iran won a spot in the World Cup soccer championship in 1998 and again during student protests in 1999.

"They decided to invest in a force that could take over the streets that didn’t look like a military deployment,” said an Iran analyst who did not want to be identified because of his involvement in the events.

The Basij was nominally part of the Revolutionary Guards, but it is a loosely allied group of organizations that range from the more official units like the Ansar Hezbollah, which undergo formal training, to many groups controlled by local clerics.

Nearly every mosque in Iran has a room marked Paygah-e-Basij or Basij base, which serves as a kind of Islamic club where students study the Koran, organize sports teams and plan field trips.

Some members are religious zealots, and some are not. Most members are lower-middle-class youths who enjoy certain benefits by joining. They can skip the required military service, can obtain reserved spots in the universities and also receive a small stipend.

No one seems to know how many people belong to the Basij, but estimates run from a few hundred thousand to more than a million. The age range is from high school to about 30 years old.

During a short-lived student protest at Tehran University in 2003, the Basijis roared around on motorcycles and were trucked in on military vehicles. They hit students with chains, lobbed bricks at their heads and beat them with long wooden truncheons.

One Basiji swung at a reporter with such force that the blow shattered a portable satellite telephone in the reporter’s pocket.

Basijis, who can be disorganized and undisciplined, have been known to beat up students for the simplest infractions of Islamic conduct. A male student at Isfahan University said he had once been beaten because he walked down the corridor to the bathroom in just his underwear; Basij students in the dormitory thought he was insufficiently modest.

President Mahmoud Ahmadinejad, after taking office in 2005, tried to create a more formal organization for the Basij, with an official budget, but the Revolutionary Guards rejected the move, Iran analysts said.

The demonstration planned for Friday by Ansar Hezbollah is expected to march on the Expediency Council, a government oversight body run by former President Ali Akbar Hashemi Rafsanjani.

Mr. Ahmadinejad attacked him and his family as corrupt during the campaign, and although he has dropped out of public sight since the election, he is widely believed to be orchestrating the opposition.

The huge numbers of people who have turned out to protest the election results in recent days have presented somewhat of a problem for the Basij: there are too many demonstrators to enable the vigilantes to intimidate people in their customary way.

At times when the Basijis have tried to attack demonstrators, the crowd has turned on them, beating the vigilantes and setting their motorcycles on fire.

New York Times