GENEVA (AFP) - Militants have made appeals for attacks against the Euro 2008 football championships on jihadist websites which worry Swiss police but they said Thursday there was no "concrete" threat yet. The championships in Switzerland and Austria start June 7 and Swiss federal police spokesman Juerg Buehler told La Liberte daily that the tournament "is a target cited by the terrorist network" on websites. "We are following the situation very closely," he said. He said similar threats were made before the World Cup in Germany in 2006, and that some attacks were planned against the rail network but were called off because security was considered too tight. "We are prepared for every eventuality," he said. A top official of European football's governing body, UEFA, told AFP that arrests, never previously announced, were also made before the 2004 European championships in Portugal. In a statement sent to AFP however, Swiss police said: "Any big event like Euro 2008 could be a target of choice for terrorists... but there are no concrete elements right now that would lean one to fear any specific danger." No extremist group has given any indication that it will target the football championships, police added. "It is clear however that how things develop in the coming weeks and months in global hotspots could have security repercussions at home," the statement said. Austrian Interior Ministry spokesman Rudolf Gollia told AFP: "Our assessments do not currently indicate any threat either in Switzerland or Austria." La Liberte said Switzerland is widely accused of Islamophobia in the Muslim world, notably because of opposition to the construction of mosque minarets in several Swiss cities. Austria could be a target because of the presence of its troops in the international force in Afghanistan. William Gaillard, advisor to Michel Platini, the UEFA president, admitted that fears of terror attacks had surfaced before the 2004 European championships.