The protesters intend to show their discontent over the re-election last month of President Mahmoud Ahmadinejad and commemorate the 10th anniversary of a violent confrontation between students and security forces. According to one circular passed around on the Internet, demonstrations are planned in over 200 Iranian cities and towns around the country. Detailed maps of gathering points and meeting places have been circulating for days, even though opposition leader Mir Hossein Mousavi has called for an end to public protests. Tehran police chief Gen. Esmail Ahmadi-Moqaddam vowed Wednesday in a statement broadcast on state television that his forces would confront any demonstration, and some officials warned that the Revolutionary Guard would be deployed to back anti-riot police and pro-government Basiji militiamen. But many in Iran say they will go ahead with the demonstrations anyway. 'A virtual campaign is in full force and nobody is able to keep it in check,' said one announcement, advising protesters to carry no weapon heavier than a rose. 'I'm going to go because it's important to keep on resisting,' said one 29-year-old woman in Tehran, speaking on condition of anonymity. 'It's a gesture of hope.' Farzad, a 28-year-old unemployed engineer in Tehran, said he and scores of friends were determined to take to the streets. He will bring a vinegar-soaked rag to ward off the effects of tear gas and said he is ready to be beaten, chased, or even jailed for a couple weeks. 'I am a mountaineer and fit to run fast in case I am chased by the militias or anti-riot police,' said Farzad, who spoke on condition his last name not be published. 'The authorities must see us. I just cannot help. I have to take to the streets tomorrow.' Ahmadinejad's re-election on June 12, marred by opposition allegations of massive vote-rigging, has created the biggest political rift within the Islamic Republic since the first years after the 1979 revolution. A movement built on Mousavi's presidential campaign continues to challenge authorities, who have attempted to crush dissent by beating and jailing protesters. On Wednesday, a prosecutor said that 500 of 2,500 people arrested in weeks of unrest remain in jail. Informal organizers of Thursday's gatherings have warned protesters to dress modestly, avoid wearing makeup, keep valuables at home and brace for confrontations with the authorities. Those skittish about heading to the streets are being encouraged to drive around honking their horns, as many families did during 2003 commemorations of the 1999 confrontation between students and authorities. Before this year's election, that student rebellion had been the most aggressive challenge to authorities since the 1979 Islamic Revolution. If nothing else, organizers are urging supporters to just walk around the city. 'Your presence on the sidewalks encourages peaceful demonstrators,' said a set of instructions posted to the Facebook page of a group supporting Mousavi. Solidarity rallies are also being planned in Europe and North America, including in front of the federal building in Los Angeles, at New York's Washington Square Park and Washington's Freedom Plaza, according to numerous Web sites and mass e-mails. 'Always bear in mind the objective: A lawful movement for regaining our sovereign rights in the presidential election,' the Facebook page said. 'Shout out Islamic slogans in a bid to strike a severe blow to violence-seekers who suppress Muslims under cover of religion. You are struggling for freedom, spirituality and human rights.' Mostaghim, a special correspondent, reported from Tehran. 