Long-simmering tensions between Lebanon's Sunni and Shi'ite Muslim communities are increasingly turning into violent street fights, often over small matters like the hanging of political posters or insults traded on the Internet - raising new fears of an Iraq-style sectarian outburst here. So far, the violence has been largely limited to street fights with fists and sticks, occurring roughly every few weeks over the last several months. Security forces have quickly intervened in each case. In the latest incident Monday night, dozens of Shi'ite rioters protesting electricity rationing blocked a major road in central Beirut and shouted anti-government slogans in a mixed Shi'ite-Sunni area, a move seen by the Sunni-led government majority as a provocation. The rioters set garbage containers ablaze and stoned some cars before troops dispersed them. The mixed neighborhood of Basta recently was a stark example of how things can go more seriously wrong. There on New Year's Eve and into the next day, Sunni and Shi'ite local men clashed with knives, sticks and stones. At least seven people were injured and several parked cars were damaged before troops, firing in the air, restored order. The Basta fight apparently started over a large poster of the Sunnis' top political leader, lawmaker Saad Hariri, and his slain father, former Premier Rafik Hariri. The picture on Al-Maamoun Street was torn down, reportedly by men from the two main Shi'ite parties, Hizbullah and Amal. A large portrait of Hizbullah's leader hangs nearby. Hariri's supporters rehung the Hariri picture the next day - this time on a building just opposite a police station in the neighborhood. The two Muslim sects together make up about 60 percent of Lebanon's 4 million population. Their dispute is rooted in the country's yearlong political standoff: Sunnis support the Western-backed government while Shi'ites favor the Syrian-backed opposition. Unlike the 1975-90 civil war, however, when Christians fought against Muslims, this time the country's Christians - about one-third of the population - are split between the Hizbullah-led opposition and the anti-Syrian parliamentary majority. Many Lebanese try to downplay the recent incidents, insisting they mean little. "What happened on New Year's Day was a kids' play. ... The next day, those who fought each other, they reconciled and kissed each other," said Jaafar Ali, a 75-year-old Shi'ite who owns a furniture store in Basta. Ali said he has been living "in peace" with his family of six in Basta for more than 30 years. Yusr Abu al-Hawa, a 45-year-old Sunni woman who runs an electric appliance shop on Al Maamoun street, also insisted there is no Sunni-Shi'ite tension. "We ... have been living in peace for years without any problem. My daughter is married to a Shi'ite," she said. But under the surface, tension is palpable. Three empty police vehicles sat on a recent day next to the building where the original picture of the Hariris had hung. A group of bearded, black-clad Hezbollah men listened on a sidewalk to taped religious chants. One intervened and took away the notes of an Associated Press reporter who was interviewing residents. "As long as political differences between leaders of both sides persist, tension will continue," warned Ahmed Bazaza, a 50-year-old Shiite grocer in Basta. The tensions began to rise after the 2005 assassination of Rafik Hariri. His supporters blamed Syria, an ally of the Shi'ites' Hizbullah faction also backed by Iran. Syria has denied involvement in that murder and other killings targeting anti-Syrian figures. The fear of further trouble has prompted top Sunni and Shiite spiritual leaders to issue religiously binding rulings prohibiting violence against fellow Muslims, and to issue a joint statement urging peace. On Tuesday, Prime Minister Fuad Saniora criticized the latest opposition protest, carried out under the pretext of economic hardships. "The Lebanese are too smart to fall for this," he said. "Such actions have been tried before and have only worsened conditions, increased incitement and threatened with sedition." The worst violence occurred a year ago, in gunfights and rioting between Shi'ites and Sunnis at a university cafeteria that left four people dead. That incident prompted the army to declare Beirut's first curfew since 1996. Last month, security forces broke up another Shi'ite-Sunni student fight at another university campus, after insults were traded on the popular Internet hangout, Facebook. And at least 25 people were injured last summer when supporters of Hizbullah and Hariri fought with sticks and stones in villages near the eastern city of Baalbek, a predominantly Shi'ite region. The tensions have filtered into sports as well. For the last two years, soccer matches have been held without spectators because of violence in stadiums between Sunnis and Shiites supporting rival teams. Politicians from both camps insist they don't want a sectarian confrontation but accuse each other of trying to cause one. Asked if he feared Iraqi-style violence, the younger Hariri said in a recent interview, "We don't want this but we know that there is very high tension ... the people are afraid of this."