The three suspected al-Qaeda members taken into custody on Friday are alleged to have been involved in a plot that represented a serious and real threat.

Their apprehension averted a "concrete and imminent danger," German Interior Minister Hans-Peter Friedrich said. Events had shown Germany remained a target for international terror networks, said Friedrich, adding it was important to remain vigilant to future threats.

Germany's Federal Criminal Police Office (BKA) worked closely with the Federal Office for the Protection of the Constitution, state police and foreign authorities in its investigation, said the minister, with the suspects under surveillance since April 15. According to the weekly news magazine, Der Spiegel, America's CIA and the Moroccan secret service had joined in the surveillance.

Further details were not immediately provided, but Deputy Federal Prosecutor Rainer Griesbaum and the head of the BKA, Joerg Ziercke, were to hold a press conference on Saturday to discuss the arrests.

"The accused will be summoned before the examining magistrate of the Federal Court of Justice on Saturday," the office of the Public Prosecutor General said in a statement.

There were reports that a large quantity of explosives had also been discovered.

Reports of plan for major attack

The three men were arrested in the western German state of North Rhine-Westphalia and are suspected of planning a major terror attack.

Investigators were classifying the dimension of the case as comparable with that of the arrest in 2007 of the so-called Sauerland group of four Islamists who were arrested on suspicion of planning a bomb attack in Germany, public broadcaster ZDF reported.

Prosecutors did not comment on the suspects' sex, nationality or where they were taken into custody.

The Interior Ministry announced in February that the state of alert would gradually be scaled back after being raised in November, when US authorities warned of an al Qaeda plan to carry out 'Mumbai-style' attacks in Germany, Britain and France.

Author: Gregg Benzow, Richard Connor (dpa, AP, AFP)

Editor: Sean Sinico