About one hundred protesters gathered on Tuesday (September 11) in front of the European Parliament in Brussels to try and demonstrate against what they called the "Islamisation" of Europe. The demonstration, organised by the "Stop the Islamisation of Europe" campaign group, was timed to coincide with the sixth anniversary of al Qaeda's Sept. 11 attacks on the United States. It was banned by the mayor of Brussels, who said it posed a threat to public order. Groups from Denmark, Britain and Germany called for supporters to gather in front of the European Parliament in Brussels and called on others to join them in what they called their fight to prevent Islam becoming a "dominant political force in Europe". There was unusually heavy security in Brussels' European district. Police threw up barbed-wire barricades around the European Parliament building and a water cannon truck was parked in a side-street. But demonstrators were outnumbered by reporters and police. Later on Tuesday, Belgian police arrested leaders of an extreme right party, Vlaams Belang, after they joined the demonstration. Frank Vanhecke, head of the anti-immigrant Vlaams Belang (Flemish Interest), was hand-cuffed by anti-riot police and taken to a police van, a Reuters photographer at the scene said. Another top party official was also detained. Critics of the demonstration said the organisers had an anti-immigrant and anti-Islam agenda.