Tension was high in Rome on Friday as the Italian capital prepared for Saturday\'s demonstration against austerity. Police forces were put on alert and the prefect of Rome, Giuseppe Pecoraro, has obtained from the interior ministry 4,000 extra men to deploy throughout the city. On Friday afternoon police officers and armoured vehicles were already positioned around possible targets of protesters such as the parliament, the Bank of Italy, the ministries of economy and infrastructure and other sensitive buildings. The main hospitals of Rome were also on alert. Mayor Ignazio Marino put a special task force to follow the events. The risk of clashes is being seen as real. \"We cannot rule it out. We are considering every scenario and we are worried about possible infiltrators among the demonstration, as it happened on October 2011,\" Pecoraro said. Two years ago, a similar protest ended in fierce clashes between a minority of young protesters and police forces, with several people injured and many shop windows, banks and cars smashed or put on fire. Authorities are trying to avoid a similar result this year. For their part, organizers of the demonstration, including a wide range of groups and organizations from varied sectors of society, would not like to see the reasons of their peaceful protest to be clouded by violence and security problems. Pecoraro has also appealed on them by saying that he counts on the same demonstrators to isolate possible violent individuals during the rally. Police checkpoints and controls have been put in force since Thursday night. Five French protesters, believed to be \"black bloc\" protesters, were stopped in Rome and expelled from the country. A van full of sticks, marbles and hammers was seized by police in the central Regina Elena Avenue, not far from a hospital and along the path the rally would be going through on Saturday. Atmosphere in Rome was already quite tense on Friday due to the national strike called by far leftist COBAS and USB unions against the coalition government of Prime Minister Enrico Letta. Public transport workers, hospital workers and civil servants took to the streets to protest the austerity measures included in the 2014 budget law, recently unveiled by the cabinet. The strike\'s attendance, however, was not as high as expected. Public transport was only partially hit and underground service ran between 30 and 50 percent in the cities of Milan, Rome and Naples, according to data released by the public Agency for Mobility. Air traffic was the most disrupted service with more than 140 flights cancelled at the Fiumicino Airport of Rome. Saturday\'s demonstration will cross the \"heart\" of the Italian capital, starting from the square of the Basilica of St. John Lateran, where some groups have begun to camp on Friday night, to end at the Porta Pia gate. Along the path, many shops and businesses are ready to close for fear of attacks by isolated thugs. \"We are worried and we appeal on protesters to respect the people who live and work in Rome,\" Giuseppe Roscioli, president of the business association Confcommercio, said on Friday. According to the police, between 15,000 and 20,000 people are expected to participate. The organizers predict at least 50,000.