German Interior Minister Otto Schily said on Sunday Europe needs to penetrate guerrilla groups and improve the co-ordination of anti-terror police work to prevent attacks like the Madrid bombings.
"We need as much information in advance as possible, we've got to be able to gather intelligence from inside these groups," Schily told German television.
In another interview with the Frankfurter Allgemeine Sonntagszeitung newspaper Schily said the terror threat will loom "for a long time" and the general public had failed to come to terms with that.
"The terrorism we're facing is an epochal threat and we need to brace for a long-term confrontation," he said. "There's a tendency to say after a terror attack 'It's over and history now'. People put it out of their minds rather quickly."
Schily told German television better co-operation on tracking the movements and contacts of guerrillas was vital.
"We have a great interest in where suspected terrorists are moving about and whom they are in contact with," Schily said.
Schily also said that Europe's anti-terror police work would benefit from greater sharing of intelligence across borders.
"We need to better compare the findings of various security forces, from police to domestic intelligence and foreign intelligence agencies, in order to get a clearer picture of what is going on in terror cells," he said. "It's a complicated process in Europe but we've made some progress."
As one example, he said that all European countries had extensive files of fingerprints and DNA material.
"An exchange of these data has to be made possible," he told the newspaper.
German crime-fighting agencies have had some success in the past infiltrating far-right neo-Nazi groups and the leftwing extremists Red Army Faction.
Over a week after more than 200 people were killed in bombings in Madrid, EU ministers agreed on Friday at an emergency meeting in Brussels to improve intelligence-sharing.
"The most important aspect of the fight against terror is prevention," Schily said. "We have no chance of frightening off fanatical murderers. Even Atta wasn't intimidated by the prospect of life in prison. These people have no conscience."
He was referring to Mohammed Atta, the suicide pilot who led a Hamburg terror cell suspected of crashing planes into the World Trade Center on September 11, 2001. He studied in Hamburg and is believed to have organised the attack from Germany.