German police were searching Thursday for about ten suspected supporters of an Islamic group linked to al-Qaida who are believed to have assisted the three militants arrested earlier this week in their foiled bomb plot, an official said.
Authorities believed "some 10" further suspects provided support to the two German converts and a Turkish citizen who were arrested Tuesday on suspicion of plotting attacks on U.S. and other facilities here, August Hanning, a top security official, told ARD broadcaster
"This is the network that we are aware of at the moment," Hanning said, adding that authorities believe the splintered cell - which includes more converted Germans, Turkish and other citizens - no longer poses a direct security threat.
The three arrested suspects had military-style detonators and enough material to make bombs more powerful than those that killed 191 people in Madrid in 2004 and 52 commuters in London two years ago, prosecutors said Wednesday.
"We were able to succeed in recognizing and preventing the most serious and massive bombings," German Federal Prosecutor Monika Harms said at a news conference. She declined to name specific targets.
In Washington, a senior U.S. State Department official said German investigators had determined the Frankfurt International Airport and the nearby U.S. Ramstein Air Base were the primary targets of the plot, but that those arrested may have also been considering strikes on other sites, particularly facilities associated with the United States.
The official spoke on condition of anonymity to describe discussions between U.S. and German intelligence agencies.
Germany's announcement was the second in two days that a major attack had been foiled in Europe, after Danish authorities arrested eight alleged Islamic militants with links to senior al-Qaida terrorists.
The German raids were launched after an intense, six-month investigation by 300 officers, who followed the suspects so closely that, at one point, police stealthily substituted a harmless alternate for the raw bomb material the suspects had collected, according to prosecutors.
German and U.S. officials have been increasingly on edge after Islamist attacks on German troops in Afghanistan, fearing an attack at home, and security measures had been increased.