Iranian security forces beat protesters in central Teheran on Saturday, a sign of mounting tensions ahead of planned opposition rallies to mark a religious festival and the death of a dissident cleric a week ago, a reformist Web site said. The Rah-e-Sabz site said forces, including the elite Revolutionary Guard and the paramilitary Basijis, used tear gas and pepper spray in an attempt to disperse demonstrators, and broke the windows of cars that were honking horns in protest. It said protests occurred in at least three areas: Imam Hossein Square, Pol-e-Choobi and Ferdowsi Square. The report could not be independently confirmed because the Iranian government has banned foreign media from covering opposition protests. Iran is marking the first 10 days of the Islamic month of Moharram, a time of mourning rituals for a revered Shi'ite saint. The period culminates Sunday with Ashoura - a day that coincides with the seventh day since the death of Iran's most senior dissident cleric, Grand Ayatollah Hossein Ali Montazeri. More memorials and possible protests are expected. The death on Sunday of the 87-year-old Montazeri, a sharp critic of Iran's leaders, has given a new push to opposition protests, which have endured despite a heavy security crackdown since disputed presidential elections in June. His memorials have brought out not only the young, urban activists who filled the ranks of earlier protests, but also older, more religious Iranians who revered Montazeri on grounds of faith as much as politics. Tens of thousands marched in his funeral procession in the holy city of Qom on Monday, many chanting slogans against the government. Violence erupted Wednesday when thousands tried to gather for a Montazeri memorial at a mosque in the central city of Isfahan, 325 kilometers south of Teheran. They were met by a large force of riot police and Basijis, and more than 50 people were arrested. Iran's police chief, Gen. Ismail Ahmadi Moghaddam, has threatened tougher action against protesters on Saturday and Sunday. Opposition leaders have used holidays and other symbolic days in recent months to stage anti-government rallies.