Fifteen vehicles were burned around Belgium overnight, the Interior Ministry said Saturday, including a bus torched near the eastern city of Liege. But the government played down fears of the kind of unrest that has hit France. "These were isolated incidents and at no time was there any question of high tension or agitation," the ministry said in a statement. "The situation is calm." Most of the vehicles torched were in Brussels. About 60 vehicles have been burned in Belgium in the past week, but the country has not seen rioting similar to that which has hit poor neighborhoods of French cities. Police were expected to add extra patrols in the center of the capital Saturday evening after a message urging youths to attack downtown shops was posted on the Internet. "The police will take the precautions necessary to handle any trouble," Interior Ministry official Fernand Koekelberg told RTBF television.